/*
* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#ifndef BR_BEARSSL_RSA_H__
#define BR_BEARSSL_RSA_H__
#include <stddef.h>
#include <stdint.h>
#include "bearssl_hash.h"
#include "bearssl_rand.h"
#ifdef __cplusplus
extern "C" {
#endif
/** \file bearssl_rsa.h
*
* # RSA
*
* This file documents the RSA implementations provided with BearSSL.
* Note that the SSL engine accesses these implementations through a
* configurable API, so it is possible to, for instance, run a SSL
* server which uses a RSA engine which is not based on this code.
*
* ## Key Elements
*
* RSA public and private keys consist in lists of big integers. All
* such integers are represented with big-endian unsigned notation:
* first byte is the most significant, and the value is positive (so
* there is no dedicated "sign bit"). Public and private key structures
* thus contain, for each such integer, a pointer to the first value byte
* (`unsigned char *`), and a length (`size_t`) which is the number of
* relevant bytes. As a general rule, minimal-length encoding is not
* enforced: values may have extra leading bytes of value 0.
*
* RSA public keys consist in two integers:
*
* - the modulus (`n`);
* - the public exponent (`e`).
*
* RSA private keys, as defined in
* [PKCS#1](https://tools.ietf.org/html/rfc3447), contain eight integers:
*
* - the modulus (`n`);
* - the public exponent (`e`);
* - the private exponent (`d`);
* - the first prime factor (`p`);
* - the second prime factor (`q`);
* - the first reduced exponent (`dp`, which is `d` modulo `p-1`);
* - the second reduced exponent (`dq`, which is `d` modulo `q-1`);
* - the CRT coefficient (`iq`, the inverse of `q` modulo `p`).
*
* However, the implementations defined in BearSSL use only five of
* these integers: `p`, `q`, `dp`, `dq` and `iq`.
*
* ## Security Features and Limitations
*
* The implementations contained in BearSSL have the following limitations
* and features:
*
* - They are constant-time. This means that the execution time and
* memory access pattern may depend on the _lengths_ of the private
* key components, but not on their value, nor on the value of
* the operand. Note that this property is not achieved through
* random masking, but "true" constant-time code.
*
* - They support only private keys with two prime factors. RSA private
* keys with three or more prime factors are nominally supported, but
* rarely used; they may offer faster operations, at the expense of
* more code and potentially a reduction in security if there are
* "too many" prime factors.
*
* - The public exponent may have arbitrary length. Of course, it is
* a good idea to keep public exponents small, so that public key
* operations are fast; but, contrary to some widely deployed
* implementations, BearSSL has no problem with public exponents
* longer than 32 bits.
*
* - The two prime factors of the modulus need not have the same length
* (but severely imbalanced factor lengths might reduce security).
* Similarly, there is no requirement that the first factor (`p`)
* be greater than the second factor (`q`).
*
* - Prime factors and modulus must be smaller than a compile-time limit.
* This is made necessary by the use of fixed-size stack buffers, and
* the limit has been adjusted to keep stack usage under 2 kB for the
* RSA operations. Currently, the maximum modulus size is 4096 bits,
* and the maximum prime factor size is 2080 bits.
*
* - The RSA functions themselves do not enforce lower size limits,
* except that which is absolutely necessary for the operation to
* mathematically make sense (e.g. a PKCS#1 v1.5 signature with
* SHA-1 requires a modulus of at least 361 bits). It is up to users
* of this code to enforce size limitations when appropriate (e.g.
* the X.509 validation engine, by default, rejects RSA keys of
* less than 1017 bits).
*
* - Within the size constraints expressed above, arbitrary bit lengths
* are supported. There is no requirement that prime factors or
* modulus have a size multiple of 8 or 16.
*
* - When verifying PKCS#1 v1.5 signatures, both variants of the hash
* function identifying header (with and without the ASN.1 NULL) are
* supported. When producing such signatures, the variant with the
* ASN.1 NULL is used.
*
* ## Implementations
*
* Three RSA implementations are included:
*
* - The **i32** implementation internally represents big integers
* as arrays of 32-bit integers. It is perfunctory and portable,
* but not very efficient.
*
* - The **i31** implementation uses 32-bit integers, each containing
* 31 bits worth of integer data. The i31 implementation is somewhat
* faster than the i32 implementation (the reduced integer size makes
* carry propagation easier) for a similar code footprint, but uses
* very slightly larger stack buffers (about 4% bigger).
*
* - The **i62** implementation is similar to the i31 implementation,
* except that it internally leverages the 64x64->128 multiplication
* opcode. This implementation is available only on architectures
* where such an opcode exists. It is much faster than i31.
*
* - The **i15** implementation uses 16-bit integers, each containing
* 15 bits worth of integer data. Multiplication results fit on
* 32 bits, so this won't use the "widening" multiplication routine
* on ARM Cortex M0/M0+, for much better performance and constant-time
* execution.
*/
/**
* \brief RSA public key.
*
* The structure references the modulus and the public exponent. Both
* integers use unsigned big-endian representation; extra leading bytes
* of value 0 are allowed.
*/
typedef struct {
/** \brief Modulus. */
unsigned char *n;
/** \brief Modulus length (in bytes). */
size_t nlen;
/** \brief Public exponent. */
unsigned char *e;
/** \brief Public exponent length (in bytes). */
size_t elen;
} br_rsa_public_key;
/**
* \brief RSA private key.
*
* The structure references the private factors, reduced private
* exponents, and CRT coefficient. It also contains the bit length of
* the modulus. The big integers use unsigned big-endian representation;
* extra leading bytes of value 0 are allowed. However, the modulus bit
* length (`n_bitlen`) MUST be exact.
*/
typedef struct {
/** \brief Modulus bit length (in bits, exact value). */
uint32_t n_bitlen;
/** \brief First prime factor. */
unsigned char *p;
/** \brief First prime factor length (in bytes). */
size_t plen;
/** \brief Second prime factor. */
unsigned char *q;
/** \brief Second prime factor length (in bytes). */
size_t qlen;
/** \brief First reduced private exponent. */
unsigned char *dp;
/** \brief First reduced private exponent length (in bytes). */
size_t dplen;
/** \brief Second reduced private exponent. */
unsigned char *dq;
/** \brief Second reduced private exponent length (in bytes). */
size_t dqlen;
/** \brief CRT coefficient. */
unsigned char *iq;
/** \brief CRT coefficient length (in bytes). */
size_t iqlen;
} br_rsa_private_key;
/**
* \brief Type for a RSA public key engine.
*
* The public key engine performs the modular exponentiation of the
* provided value with the public exponent. The value is modified in
* place.
*
* The value length (`xlen`) is verified to have _exactly_ the same
* length as the modulus (actual modulus length, without extra leading
* zeros in the modulus representation in memory). If the length does
* not match, then this function returns 0 and `x[]` is unmodified.
*
* It `xlen` is correct, then `x[]` is modified. Returned value is 1
* on success, 0 on error. Error conditions include an oversized `x[]`
* (the array has the same length as the modulus, but the numerical value
* is not lower than the modulus) and an invalid modulus (e.g. an even
* integer). If an error is reported, then the new contents of `x[]` are
* unspecified.
*
* \param x operand to exponentiate.
* \param xlen length of the operand (in bytes).
* \param pk RSA public key.
* \return 1 on success, 0 on error.
*/
typedef uint32_t (*br_rsa_public)(unsigned char *x, size_t xlen,
const br_rsa_public_key *pk);
/**
* \brief Type for a RSA signature verification engine (PKCS#1 v1.5).
*
* Parameters are:
*
* - The signature itself. The provided array is NOT modified.
*
* - The encoded OID for the hash function. The provided array must begin
* with a single byte that contains the length of the OID value (in
* bytes), followed by exactly that many bytes. This parameter may
* also be `NULL`, in which case the raw hash value should be used
* with the PKCS#1 v1.5 "type 1" padding (as used in SSL/TLS up
* to TLS-1.1, with a 36-byte hash value).
*
* - The hash output length, in bytes.
*
* - The public key.
*
* - An output buffer for the hash value. The caller must still compare
* it with the hash of the data over which the signature is computed.
*
* **Constraints:**
*
* - Hash length MUST be no more than 64 bytes.
*
* - OID value length MUST be no more than 32 bytes (i.e. `hash_oid[0]`
* must have a value in the 0..32 range, inclusive).
*
* This function verifies that the signature length (`xlen`) matches the
* modulus length (this function returns 0 on mismatch). If the modulus
* size exceeds the maximum supported RSA size, then the function also
* returns 0.
*
* Returned value is 1 on success, 0 on error.
*
* Implementations of this type need not be constant-time.
*
* \param x signature buffer.
* \param xlen signature length (in bytes).
* \param hash_oid encoded hash algorithm OID (or `NULL`).
* \param hash_len expected hash value length (in bytes).
* \param pk RSA public key.
* \param hash_out output buffer for the hash value.
* \return 1 on success, 0 on error.
*/
typedef uint32_t (*br_rsa_pkcs1_vrfy)(const unsigned char *x, size_t xlen,
const unsigned char *hash_oid, size_t hash_len,
const br_rsa_public_key *pk, unsigned char *hash_out);
/**
* \brief Type for a RSA signature verification engine (PSS).
*
* Parameters are:
*
* - The signature itself. The provided array is NOT modified.
*
* - The hash function which was used to hash the message.
*
* - The hash function to use with MGF1 within the PSS padding. This
* is not necessarily the same hash function as the one which was
* used to hash the signed message.
*
* - The hashed message (as an array of bytes).
*
* - The PSS salt length (in bytes).
*
* - The public key.
*
* **Constraints:**
*
* - Hash message length MUST be no more than 64 bytes.
*
* Note that, contrary to PKCS#1 v1.5 signature, the hash value of the
* signed data cannot be extracted from the signature; it must be
* provided to the verification function.
*
* This function verifies that the signature length (`xlen`) matches the
* modulus length (this function returns 0 on mismatch). If the modulus
* size exceeds the maximum supported RSA size, then the function also
* returns 0.
*
* Returned value is 1 on success, 0 on error.
*
* Implementations of this type need not be constant-time.
*
* \param x signature buffer.
* \param xlen signature length (in bytes).
* \param hf_data hash function applied on the message.
* \param hf_mgf1 hash function to use with MGF1.
* \param hash hash value of the signed message.
* \param salt_len PSS salt length (in bytes).
* \param pk RSA public key.
* \return 1 on success, 0 on error.
*/
typedef uint32_t (*br_rsa_pss_vrfy)(const unsigned char *x, size_t xlen,
const br_hash_class *hf_data, const br_hash_class *hf_mgf1,
const void *hash, size_t salt_len, const br_rsa_public_key *pk);
/**
* \brief Type for a RSA encryption engine (OAEP).
*
* Parameters are:
*
* - A source of random bytes. The source must be already initialized.
*
* - A hash function, used internally with the mask generation function
* (MGF1).
*
* - A label. The `label` pointer may be `NULL` if `label_len` is zero
* (an empty label, which is the default in PKCS#1 v2.2).
*
* - The public key.
*
* - The destination buffer. Its maximum length (in bytes) is provided;
* if that length is lower than the public key length, then an error
* is reported.
*
* - The source message.
*
* The encrypted message output has exactly the same length as the modulus
* (mathematical length, in bytes, not counting extra leading zeros in the
* modulus representation in the public key).
*
* The source message (`src`, length `src_len`) may overlap with the
* destination buffer (`dst`, length `dst_max_len`).
*
* This function returns the actual encrypted message length, in bytes;
* on error, zero is returned. An error is reported if the output buffer
* is not large enough, or the public is invalid, or the public key
* modulus exceeds the maximum supported RSA size.
*
* \param rnd source of random bytes.
* \param dig hash function to use with MGF1.
* \param label label value (may be `NULL` if `label_len` is zero).
* \param label_len label length, in bytes.
* \param pk RSA public key.
* \param dst destination buffer.
* \param dst_max_len destination buffer length (maximum encrypted data size).
* \param src message to encrypt.
* \param src_len source message length (in bytes).
* \return encrypted message length (in bytes), or 0 on error.
*/
typedef size_t (*br_rsa_oaep_encrypt)(
const br_prng_class **rnd, const br_hash_class *dig,
const void *label, size_t label_len,
const br_rsa_public_key *pk,
void *dst, size_t dst_max_len,
const void *src, size_t src_len);
/**
* \brief Type for a RSA private key engine.
*
* The `x[]` buffer is modified in place, and its length is inferred from
* the modulus length (`x[]` is assumed to have a length of
* `(sk->n_bitlen+7)/8` bytes).
*
* Returned value is 1 on success, 0 on error.
*
* \param x operand to exponentiate.
* \param sk RSA private key.
* \return 1 on success, 0 on error.
*/
typedef uint32_t (*br_rsa_private)(unsigned char *x,
const br_rsa_private_key *sk);
/**
* \brief Type for a RSA signature generation engine (PKCS#1 v1.5).
*
* Parameters are:
*
* - The encoded OID for the hash function. The provided array must begin
* with a single byte that contains the length of the OID value (in
* bytes), followed by exactly that many bytes. This parameter may
* also be `NULL`, in which case the raw hash value should be used
* with the PKCS#1 v1.5 "type 1" padding (as used in SSL/TLS up
* to TLS-1.1, with a 36-byte hash value).
*
* - The hash value computes over the data to sign (its length is
* expressed in bytes).
*
* - The RSA private key.
*
* - The output buffer, that receives the signature.
*
* Returned value is 1 on success, 0 on error. Error conditions include
* a too small modulus for the provided hash OID and value, or some
* invalid key parameters. The signature length is exactly
* `(sk->n_bitlen+7)/8` bytes.
*
* This function is expected to be constant-time with regards to the
* private key bytes (lengths of the modulus and the individual factors
* may leak, though) and to the hashed data.
*
* \param hash_oid encoded hash algorithm OID (or `NULL`).
* \param hash hash value.
* \param hash_len hash value length (in bytes).
* \param sk RSA private key.
* \param x output buffer for the signature value.
* \return 1 on success, 0 on error.
*/
typedef uint32_t (*br_rsa_pkcs1_sign)(const unsigned char *hash_oid,
const unsigned char *hash, size_t hash_len,
const br_rsa_private_key *sk, unsigned char *x);
/**
* \brief Type for a RSA signature generation engine (PSS).
*
* Parameters are:
*
* - An initialized PRNG for salt generation. If the salt length is
* zero (`salt_len` parameter), then the PRNG is optional (this is
* not the typical case, as the security proof of RSA/PSS is
* tighter when a non-empty salt is used).
*
* - The hash function which was used to hash the message.
*
* - The hash function to use with MGF1 within the PSS padding. This
* is not necessarily the same function as the one used to hash the
* message.
*
* - The hashed message.
*
* - The salt length, in bytes.
*
* - The RSA private key.
*
* - The output buffer, that receives the signature.
*
* Returned value is 1 on success, 0 on error. Error conditions include
* a too small modulus for the provided hash and salt lengths, or some
* invalid key parameters. The signature length is exactly
* `(sk->n_bitlen+7)/8` bytes.
*
* This function is expected to be constant-time with regards to the
* private key bytes (lengths of the modulus and the individual factors
* may leak, though) and to the hashed data.
*
* \param rng PRNG for salt generation (`NULL` if `salt_len` is zero).
* \param hf_data hash function used to hash the signed data.
* \param hf_mgf1 hash function to use with MGF1.
* \param hash hashed message.
* \param salt_len salt length (in bytes).
* \param sk RSA private key.
* \param x output buffer for the signature value.
* \return 1 on success, 0 on error.
*/
typedef uint32_t (*br_rsa_pss_sign)(const br_prng_class **rng,
const br_hash_class *hf_data, const br_hash_class *hf_mgf1,
const unsigned char *hash_value, size_t salt_len,
const br_rsa_private_key *sk, unsigned char *x);
/**
* \brief Encoded OID for SHA-1 (in RSA PKCS#1 signatures).
*/
#define BR_HASH_OID_SHA1 \
((const unsigned char *)"\x05\x2B\x0E\x03\x02\x1A")
/**
* \brief Encoded OID for SHA-224 (in RSA PKCS#1 signatures).
*/
#define BR_HASH_OID_SHA224 \
((const unsigned char *)"\x09\x60\x86\x48\x01\x65\x03\x04\x02\x04")
/**
* \brief Encoded OID for SHA-256 (in RSA PKCS#1 signatures).
*/
#define BR_HASH_OID_SHA256 \
((const unsigned char *)"\x09\x60\x86\x48\x01\x65\x03\x04\x02\x01")
/**
* \brief Encoded OID for SHA-384 (in RSA PKCS#1 signatures).
*/
#define BR_HASH_OID_SHA384 \
((const unsigned char *)"\x09\x60\x86\x48\x01\x65\x03\x04\x02\x02")
/**
* \brief Encoded OID for SHA-512 (in RSA PKCS#1 signatures).
*/
#define BR_HASH_OID_SHA512 \
((const unsigned char *)"\x09\x60\x86\x48\x01\x65\x03\x04\x02\x03")
/**
* \brief Type for a RSA decryption engine (OAEP).
*
* Parameters are:
*
* - A hash function, used internally with the mask generation function
* (MGF1).
*
* - A label. The `label` pointer may be `NULL` if `label_len` is zero
* (an empty label, which is the default in PKCS#1 v2.2).
*
* - The private key.
*
* - The source and destination buffer. The buffer initially contains
* the encrypted message; the buffer contents are altered, and the
* decrypted message is written at the start of that buffer
* (decrypted message is always shorter than the encrypted message).
*
* If decryption fails in any way, then `*len` is unmodified, and the
* function returns 0. Otherwise, `*len` is set to the decrypted message
* length, and 1 is returned. The implementation is responsible for
* checking that the input message length matches the key modulus length,
* and that the padding is correct.
*
* Implementations MUST use constant-time check of the validity of the
* OAEP padding, at least until the leading byte and hash value have
* been checked. Whether overall decryption worked, and the length of
* the decrypted message, may leak.
*
* \param dig hash function to use with MGF1.
* \param label label value (may be `NULL` if `label_len` is zero).
* \param label_len label length, in bytes.
* \param sk RSA private key.
* \param data input/output buffer.
* \param len encrypted/decrypted message length.
* \return 1 on success, 0 on error.
*/
typedef uint32_t (*br_rsa_oaep_decrypt)(
const br_hash_class *dig, const void *label, size_t label_len,
const br_rsa_private_key *sk, void *data, size_t *len);
/*
* RSA "i32" engine. Integers are internally represented as arrays of
* 32-bit integers, and the core multiplication primitive is the
* 32x32->64 multiplication.
*/
/**
* \brief RSA public key engine "i32".
*
* \see br_rsa_public
*
* \param x operand to exponentiate.
* \param xlen length of the operand (in bytes).
* \param pk RSA public key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i32_public(unsigned char *x, size_t xlen,
const br_rsa_public_key *pk);
/**
* \brief RSA signature verification engine "i32" (PKCS#1 v1.5 signatures).
*
* \see br_rsa_pkcs1_vrfy
*
* \param x signature buffer.
* \param xlen signature length (in bytes).
* \param hash_oid encoded hash algorithm OID (or `NULL`).
* \param hash_len expected hash value length (in bytes).
* \param pk RSA public key.
* \param hash_out output buffer for the hash value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i32_pkcs1_vrfy(const unsigned char *x, size_t xlen,
const unsigned char *hash_oid, size_t hash_len,
const br_rsa_public_key *pk, unsigned char *hash_out);
/**
* \brief RSA signature verification engine "i32" (PSS signatures).
*
* \see br_rsa_pss_vrfy
*
* \param x signature buffer.
* \param xlen signature length (in bytes).
* \param hf_data hash function applied on the message.
* \param hf_mgf1 hash function to use with MGF1.
* \param hash hash value of the signed message.
* \param salt_len PSS salt length (in bytes).
* \param pk RSA public key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i32_pss_vrfy(const unsigned char *x, size_t xlen,
const br_hash_class *hf_data, const br_hash_class *hf_mgf1,
const void *hash, size_t salt_len, const br_rsa_public_key *pk);
/**
* \brief RSA private key engine "i32".
*
* \see br_rsa_private
*
* \param x operand to exponentiate.
* \param sk RSA private key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i32_private(unsigned char *x,
const br_rsa_private_key *sk);
/**
* \brief RSA signature generation engine "i32" (PKCS#1 v1.5 signatures).
*
* \see br_rsa_pkcs1_sign
*
* \param hash_oid encoded hash algorithm OID (or `NULL`).
* \param hash hash value.
* \param hash_len hash value length (in bytes).
* \param sk RSA private key.
* \param x output buffer for the hash value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i32_pkcs1_sign(const unsigned char *hash_oid,
const unsigned char *hash, size_t hash_len,
const br_rsa_private_key *sk, unsigned char *x);
/**
* \brief RSA signature generation engine "i32" (PSS signatures).
*
* \see br_rsa_pss_sign
*
* \param rng PRNG for salt generation (`NULL` if `salt_len` is zero).
* \param hf_data hash function used to hash the signed data.
* \param hf_mgf1 hash function to use with MGF1.
* \param hash hashed message.
* \param salt_len salt length (in bytes).
* \param sk RSA private key.
* \param x output buffer for the signature value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i32_pss_sign(const br_prng_class **rng,
const br_hash_class *hf_data, const br_hash_class *hf_mgf1,
const unsigned char *hash_value, size_t salt_len,
const br_rsa_private_key *sk, unsigned char *x);
/*
* RSA "i31" engine. Similar to i32, but only 31 bits are used per 32-bit
* word. This uses slightly more stack space (about 4% more) and code
* space, but it quite faster.
*/
/**
* \brief RSA public key engine "i31".
*
* \see br_rsa_public
*
* \param x operand to exponentiate.
* \param xlen length of the operand (in bytes).
* \param pk RSA public key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i31_public(unsigned char *x, size_t xlen,
const br_rsa_public_key *pk);
/**
* \brief RSA signature verification engine "i31" (PKCS#1 v1.5 signatures).
*
* \see br_rsa_pkcs1_vrfy
*
* \param x signature buffer.
* \param xlen signature length (in bytes).
* \param hash_oid encoded hash algorithm OID (or `NULL`).
* \param hash_len expected hash value length (in bytes).
* \param pk RSA public key.
* \param hash_out output buffer for the hash value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i31_pkcs1_vrfy(const unsigned char *x, size_t xlen,
const unsigned char *hash_oid, size_t hash_len,
const br_rsa_public_key *pk, unsigned char *hash_out);
/**
* \brief RSA signature verification engine "i31" (PSS signatures).
*
* \see br_rsa_pss_vrfy
*
* \param x signature buffer.
* \param xlen signature length (in bytes).
* \param hf_data hash function applied on the message.
* \param hf_mgf1 hash function to use with MGF1.
* \param hash hash value of the signed message.
* \param salt_len PSS salt length (in bytes).
* \param pk RSA public key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i31_pss_vrfy(const unsigned char *x, size_t xlen,
const br_hash_class *hf_data, const br_hash_class *hf_mgf1,
const void *hash, size_t salt_len, const br_rsa_public_key *pk);
/**
* \brief RSA private key engine "i31".
*
* \see br_rsa_private
*
* \param x operand to exponentiate.
* \param sk RSA private key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i31_private(unsigned char *x,
const br_rsa_private_key *sk);
/**
* \brief RSA signature generation engine "i31" (PKCS#1 v1.5 signatures).
*
* \see br_rsa_pkcs1_sign
*
* \param hash_oid encoded hash algorithm OID (or `NULL`).
* \param hash hash value.
* \param hash_len hash value length (in bytes).
* \param sk RSA private key.
* \param x output buffer for the hash value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i31_pkcs1_sign(const unsigned char *hash_oid,
const unsigned char *hash, size_t hash_len,
const br_rsa_private_key *sk, unsigned char *x);
/**
* \brief RSA signature generation engine "i31" (PSS signatures).
*
* \see br_rsa_pss_sign
*
* \param rng PRNG for salt generation (`NULL` if `salt_len` is zero).
* \param hf_data hash function used to hash the signed data.
* \param hf_mgf1 hash function to use with MGF1.
* \param hash hashed message.
* \param salt_len salt length (in bytes).
* \param sk RSA private key.
* \param x output buffer for the signature value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i31_pss_sign(const br_prng_class **rng,
const br_hash_class *hf_data, const br_hash_class *hf_mgf1,
const unsigned char *hash_value, size_t salt_len,
const br_rsa_private_key *sk, unsigned char *x);
/*
* RSA "i62" engine. Similar to i31, but internal multiplication use
* 64x64->128 multiplications. This is available only on architecture
* that offer such an opcode.
*/
/**
* \brief RSA public key engine "i62".
*
* This function is defined only on architecture that offer a 64x64->128
* opcode. Use `br_rsa_i62_public_get()` to dynamically obtain a pointer
* to that function.
*
* \see br_rsa_public
*
* \param x operand to exponentiate.
* \param xlen length of the operand (in bytes).
* \param pk RSA public key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i62_public(unsigned char *x, size_t xlen,
const br_rsa_public_key *pk);
/**
* \brief RSA signature verification engine "i62" (PKCS#1 v1.5 signatures).
*
* This function is defined only on architecture that offer a 64x64->128
* opcode. Use `br_rsa_i62_pkcs1_vrfy_get()` to dynamically obtain a pointer
* to that function.
*
* \see br_rsa_pkcs1_vrfy
*
* \param x signature buffer.
* \param xlen signature length (in bytes).
* \param hash_oid encoded hash algorithm OID (or `NULL`).
* \param hash_len expected hash value length (in bytes).
* \param pk RSA public key.
* \param hash_out output buffer for the hash value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i62_pkcs1_vrfy(const unsigned char *x, size_t xlen,
const unsigned char *hash_oid, size_t hash_len,
const br_rsa_public_key *pk, unsigned char *hash_out);
/**
* \brief RSA signature verification engine "i62" (PSS signatures).
*
* This function is defined only on architecture that offer a 64x64->128
* opcode. Use `br_rsa_i62_pss_vrfy_get()` to dynamically obtain a pointer
* to that function.
*
* \see br_rsa_pss_vrfy
*
* \param x signature buffer.
* \param xlen signature length (in bytes).
* \param hf_data hash function applied on the message.
* \param hf_mgf1 hash function to use with MGF1.
* \param hash hash value of the signed message.
* \param salt_len PSS salt length (in bytes).
* \param pk RSA public key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i62_pss_vrfy(const unsigned char *x, size_t xlen,
const br_hash_class *hf_data, const br_hash_class *hf_mgf1,
const void *hash, size_t salt_len, const br_rsa_public_key *pk);
/**
* \brief RSA private key engine "i62".
*
* This function is defined only on architecture that offer a 64x64->128
* opcode. Use `br_rsa_i62_private_get()` to dynamically obtain a pointer
* to that function.
*
* \see br_rsa_private
*
* \param x operand to exponentiate.
* \param sk RSA private key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i62_private(unsigned char *x,
const br_rsa_private_key *sk);
/**
* \brief RSA signature generation engine "i62" (PKCS#1 v1.5 signatures).
*
* This function is defined only on architecture that offer a 64x64->128
* opcode. Use `br_rsa_i62_pkcs1_sign_get()` to dynamically obtain a pointer
* to that function.
*
* \see br_rsa_pkcs1_sign
*
* \param hash_oid encoded hash algorithm OID (or `NULL`).
* \param hash hash value.
* \param hash_len hash value length (in bytes).
* \param sk RSA private key.
* \param x output buffer for the hash value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i62_pkcs1_sign(const unsigned char *hash_oid,
const unsigned char *hash, size_t hash_len,
const br_rsa_private_key *sk, unsigned char *x);
/**
* \brief RSA signature generation engine "i62" (PSS signatures).
*
* This function is defined only on architecture that offer a 64x64->128
* opcode. Use `br_rsa_i62_pss_sign_get()` to dynamically obtain a pointer
* to that function.
*
* \see br_rsa_pss_sign
*
* \param rng PRNG for salt generation (`NULL` if `salt_len` is zero).
* \param hf_data hash function used to hash the signed data.
* \param hf_mgf1 hash function to use with MGF1.
* \param hash hashed message.
* \param salt_len salt length (in bytes).
* \param sk RSA private key.
* \param x output buffer for the signature value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i62_pss_sign(const br_prng_class **rng,
const br_hash_class *hf_data, const br_hash_class *hf_mgf1,
const unsigned char *hash_value, size_t salt_len,
const br_rsa_private_key *sk, unsigned char *x);
/**
* \brief Get the RSA "i62" implementation (public key operations),
* if available.
*
* \return the implementation, or 0.
*/
br_rsa_public br_rsa_i62_public_get(void);
/**
* \brief Get the RSA "i62" implementation (PKCS#1 v1.5 signature verification),
* if available.
*
* \return the implementation, or 0.
*/
br_rsa_pkcs1_vrfy br_rsa_i62_pkcs1_vrfy_get(void);
/**
* \brief Get the RSA "i62" implementation (PSS signature verification),
* if available.
*
* \return the implementation, or 0.
*/
br_rsa_pss_vrfy br_rsa_i62_pss_vrfy_get(void);
/**
* \brief Get the RSA "i62" implementation (private key operations),
* if available.
*
* \return the implementation, or 0.
*/
br_rsa_private br_rsa_i62_private_get(void);
/**
* \brief Get the RSA "i62" implementation (PKCS#1 v1.5 signature generation),
* if available.
*
* \return the implementation, or 0.
*/
br_rsa_pkcs1_sign br_rsa_i62_pkcs1_sign_get(void);
/**
* \brief Get the RSA "i62" implementation (PSS signature generation),
* if available.
*
* \return the implementation, or 0.
*/
br_rsa_pss_sign br_rsa_i62_pss_sign_get(void);
/**
* \brief Get the RSA "i62" implementation (OAEP encryption),
* if available.
*
* \return the implementation, or 0.
*/
br_rsa_oaep_encrypt br_rsa_i62_oaep_encrypt_get(void);
/**
* \brief Get the RSA "i62" implementation (OAEP decryption),
* if available.
*
* \return the implementation, or 0.
*/
br_rsa_oaep_decrypt br_rsa_i62_oaep_decrypt_get(void);
/*
* RSA "i15" engine. Integers are represented as 15-bit integers, so
* the code uses only 32-bit multiplication (no 64-bit result), which
* is vastly faster (and constant-time) on the ARM Cortex M0/M0+.
*/
/**
* \brief RSA public key engine "i15".
*
* \see br_rsa_public
*
* \param x operand to exponentiate.
* \param xlen length of the operand (in bytes).
* \param pk RSA public key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i15_public(unsigned char *x, size_t xlen,
const br_rsa_public_key *pk);
/**
* \brief RSA signature verification engine "i15" (PKCS#1 v1.5 signatures).
*
* \see br_rsa_pkcs1_vrfy
*
* \param x signature buffer.
* \param xlen signature length (in bytes).
* \param hash_oid encoded hash algorithm OID (or `NULL`).
* \param hash_len expected hash value length (in bytes).
* \param pk RSA public key.
* \param hash_out output buffer for the hash value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i15_pkcs1_vrfy(const unsigned char *x, size_t xlen,
const unsigned char *hash_oid, size_t hash_len,
const br_rsa_public_key *pk, unsigned char *hash_out);
/**
* \brief RSA signature verification engine "i15" (PSS signatures).
*
* \see br_rsa_pss_vrfy
*
* \param x signature buffer.
* \param xlen signature length (in bytes).
* \param hf_data hash function applied on the message.
* \param hf_mgf1 hash function to use with MGF1.
* \param hash hash value of the signed message.
* \param salt_len PSS salt length (in bytes).
* \param pk RSA public key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i15_pss_vrfy(const unsigned char *x, size_t xlen,
const br_hash_class *hf_data, const br_hash_class *hf_mgf1,
const void *hash, size_t salt_len, const br_rsa_public_key *pk);
/**
* \brief RSA private key engine "i15".
*
* \see br_rsa_private
*
* \param x operand to exponentiate.
* \param sk RSA private key.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i15_private(unsigned char *x,
const br_rsa_private_key *sk);
/**
* \brief RSA signature generation engine "i15" (PKCS#1 v1.5 signatures).
*
* \see br_rsa_pkcs1_sign
*
* \param hash_oid encoded hash algorithm OID (or `NULL`).
* \param hash hash value.
* \param hash_len hash value length (in bytes).
* \param sk RSA private key.
* \param x output buffer for the hash value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i15_pkcs1_sign(const unsigned char *hash_oid,
const unsigned char *hash, size_t hash_len,
const br_rsa_private_key *sk, unsigned char *x);
/**
* \brief RSA signature generation engine "i15" (PSS signatures).
*
* \see br_rsa_pss_sign
*
* \param rng PRNG for salt generation (`NULL` if `salt_len` is zero).
* \param hf_data hash function used to hash the signed data.
* \param hf_mgf1 hash function to use with MGF1.
* \param hash hashed message.
* \param salt_len salt length (in bytes).
* \param sk RSA private key.
* \param x output buffer for the signature value.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i15_pss_sign(const br_prng_class **rng,
const br_hash_class *hf_data, const br_hash_class *hf_mgf1,
const unsigned char *hash_value, size_t salt_len,
const br_rsa_private_key *sk, unsigned char *x);
/**
* \brief Get "default" RSA implementation (public-key operations).
*
* This returns the preferred implementation of RSA (public-key operations)
* on the current system.
*
* \return the default implementation.
*/
br_rsa_public br_rsa_public_get_default(void);
/**
* \brief Get "default" RSA implementation (private-key operations).
*
* This returns the preferred implementation of RSA (private-key operations)
* on the current system.
*
* \return the default implementation.
*/
br_rsa_private br_rsa_private_get_default(void);
/**
* \brief Get "default" RSA implementation (PKCS#1 v1.5 signature verification).
*
* This returns the preferred implementation of RSA (signature verification)
* on the current system.
*
* \return the default implementation.
*/
br_rsa_pkcs1_vrfy br_rsa_pkcs1_vrfy_get_default(void);
/**
* \brief Get "default" RSA implementation (PSS signature verification).
*
* This returns the preferred implementation of RSA (signature verification)
* on the current system.
*
* \return the default implementation.
*/
br_rsa_pss_vrfy br_rsa_pss_vrfy_get_default(void);
/**
* \brief Get "default" RSA implementation (PKCS#1 v1.5 signature generation).
*
* This returns the preferred implementation of RSA (signature generation)
* on the current system.
*
* \return the default implementation.
*/
br_rsa_pkcs1_sign br_rsa_pkcs1_sign_get_default(void);
/**
* \brief Get "default" RSA implementation (PSS signature generation).
*
* This returns the preferred implementation of RSA (signature generation)
* on the current system.
*
* \return the default implementation.
*/
br_rsa_pss_sign br_rsa_pss_sign_get_default(void);
/**
* \brief Get "default" RSA implementation (OAEP encryption).
*
* This returns the preferred implementation of RSA (OAEP encryption)
* on the current system.
*
* \return the default implementation.
*/
br_rsa_oaep_encrypt br_rsa_oaep_encrypt_get_default(void);
/**
* \brief Get "default" RSA implementation (OAEP decryption).
*
* This returns the preferred implementation of RSA (OAEP decryption)
* on the current system.
*
* \return the default implementation.
*/
br_rsa_oaep_decrypt br_rsa_oaep_decrypt_get_default(void);
/**
* \brief RSA decryption helper, for SSL/TLS.
*
* This function performs the RSA decryption for a RSA-based key exchange
* in a SSL/TLS server. The provided RSA engine is used. The `data`
* parameter points to the value to decrypt, of length `len` bytes. On
* success, the 48-byte pre-master secret is copied into `data`, starting
* at the first byte of that buffer; on error, the contents of `data`
* become indeterminate.
*
* This function first checks that the provided value length (`len`) is
* not lower than 59 bytes, and matches the RSA modulus length; if neither
* of this property is met, then this function returns 0 and the buffer
* is unmodified.
*
* Otherwise, decryption and then padding verification are performed, both
* in constant-time. A decryption error, or a bad padding, or an
* incorrect decrypted value length are reported with a returned value of
* 0; on success, 1 is returned. The caller (SSL server engine) is supposed
* to proceed with a random pre-master secret in case of error.
*
* \param core RSA private key engine.
* \param sk RSA private key.
* \param data input/output buffer.
* \param len length (in bytes) of the data to decrypt.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_ssl_decrypt(br_rsa_private core, const br_rsa_private_key *sk,
unsigned char *data, size_t len);
/**
* \brief RSA encryption (OAEP) with the "i15" engine.
*
* \see br_rsa_oaep_encrypt
*
* \param rnd source of random bytes.
* \param dig hash function to use with MGF1.
* \param label label value (may be `NULL` if `label_len` is zero).
* \param label_len label length, in bytes.
* \param pk RSA public key.
* \param dst destination buffer.
* \param dst_max_len destination buffer length (maximum encrypted data size).
* \param src message to encrypt.
* \param src_len source message length (in bytes).
* \return encrypted message length (in bytes), or 0 on error.
*/
size_t br_rsa_i15_oaep_encrypt(
const br_prng_class **rnd, const br_hash_class *dig,
const void *label, size_t label_len,
const br_rsa_public_key *pk,
void *dst, size_t dst_max_len,
const void *src, size_t src_len);
/**
* \brief RSA decryption (OAEP) with the "i15" engine.
*
* \see br_rsa_oaep_decrypt
*
* \param dig hash function to use with MGF1.
* \param label label value (may be `NULL` if `label_len` is zero).
* \param label_len label length, in bytes.
* \param sk RSA private key.
* \param data input/output buffer.
* \param len encrypted/decrypted message length.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i15_oaep_decrypt(
const br_hash_class *dig, const void *label, size_t label_len,
const br_rsa_private_key *sk, void *data, size_t *len);
/**
* \brief RSA encryption (OAEP) with the "i31" engine.
*
* \see br_rsa_oaep_encrypt
*
* \param rnd source of random bytes.
* \param dig hash function to use with MGF1.
* \param label label value (may be `NULL` if `label_len` is zero).
* \param label_len label length, in bytes.
* \param pk RSA public key.
* \param dst destination buffer.
* \param dst_max_len destination buffer length (maximum encrypted data size).
* \param src message to encrypt.
* \param src_len source message length (in bytes).
* \return encrypted message length (in bytes), or 0 on error.
*/
size_t br_rsa_i31_oaep_encrypt(
const br_prng_class **rnd, const br_hash_class *dig,
const void *label, size_t label_len,
const br_rsa_public_key *pk,
void *dst, size_t dst_max_len,
const void *src, size_t src_len);
/**
* \brief RSA decryption (OAEP) with the "i31" engine.
*
* \see br_rsa_oaep_decrypt
*
* \param dig hash function to use with MGF1.
* \param label label value (may be `NULL` if `label_len` is zero).
* \param label_len label length, in bytes.
* \param sk RSA private key.
* \param data input/output buffer.
* \param len encrypted/decrypted message length.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i31_oaep_decrypt(
const br_hash_class *dig, const void *label, size_t label_len,
const br_rsa_private_key *sk, void *data, size_t *len);
/**
* \brief RSA encryption (OAEP) with the "i32" engine.
*
* \see br_rsa_oaep_encrypt
*
* \param rnd source of random bytes.
* \param dig hash function to use with MGF1.
* \param label label value (may be `NULL` if `label_len` is zero).
* \param label_len label length, in bytes.
* \param pk RSA public key.
* \param dst destination buffer.
* \param dst_max_len destination buffer length (maximum encrypted data size).
* \param src message to encrypt.
* \param src_len source message length (in bytes).
* \return encrypted message length (in bytes), or 0 on error.
*/
size_t br_rsa_i32_oaep_encrypt(
const br_prng_class **rnd, const br_hash_class *dig,
const void *label, size_t label_len,
const br_rsa_public_key *pk,
void *dst, size_t dst_max_len,
const void *src, size_t src_len);
/**
* \brief RSA decryption (OAEP) with the "i32" engine.
*
* \see br_rsa_oaep_decrypt
*
* \param dig hash function to use with MGF1.
* \param label label value (may be `NULL` if `label_len` is zero).
* \param label_len label length, in bytes.
* \param sk RSA private key.
* \param data input/output buffer.
* \param len encrypted/decrypted message length.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i32_oaep_decrypt(
const br_hash_class *dig, const void *label, size_t label_len,
const br_rsa_private_key *sk, void *data, size_t *len);
/**
* \brief RSA encryption (OAEP) with the "i62" engine.
*
* This function is defined only on architecture that offer a 64x64->128
* opcode. Use `br_rsa_i62_oaep_encrypt_get()` to dynamically obtain a pointer
* to that function.
*
* \see br_rsa_oaep_encrypt
*
* \param rnd source of random bytes.
* \param dig hash function to use with MGF1.
* \param label label value (may be `NULL` if `label_len` is zero).
* \param label_len label length, in bytes.
* \param pk RSA public key.
* \param dst destination buffer.
* \param dst_max_len destination buffer length (maximum encrypted data size).
* \param src message to encrypt.
* \param src_len source message length (in bytes).
* \return encrypted message length (in bytes), or 0 on error.
*/
size_t br_rsa_i62_oaep_encrypt(
const br_prng_class **rnd, const br_hash_class *dig,
const void *label, size_t label_len,
const br_rsa_public_key *pk,
void *dst, size_t dst_max_len,
const void *src, size_t src_len);
/**
* \brief RSA decryption (OAEP) with the "i62" engine.
*
* This function is defined only on architecture that offer a 64x64->128
* opcode. Use `br_rsa_i62_oaep_decrypt_get()` to dynamically obtain a pointer
* to that function.
*
* \see br_rsa_oaep_decrypt
*
* \param dig hash function to use with MGF1.
* \param label label value (may be `NULL` if `label_len` is zero).
* \param label_len label length, in bytes.
* \param sk RSA private key.
* \param data input/output buffer.
* \param len encrypted/decrypted message length.
* \return 1 on success, 0 on error.
*/
uint32_t br_rsa_i62_oaep_decrypt(
const br_hash_class *dig, const void *label, size_t label_len,
const br_rsa_private_key *sk, void *data, size_t *len);
/**
* \brief Get buffer size to hold RSA private key elements.
*
* This macro returns the length (in bytes) of the buffer needed to
* receive the elements of a RSA private key, as generated by one of
* the `br_rsa_*_keygen()` functions. If the provided size is a constant
* expression, then the whole macro evaluates to a constant expression.
*
* \param size target key size (modulus size, in bits)
* \return the length of the private key buffer, in bytes.
*/
#define BR_RSA_KBUF_PRIV_SIZE(size) (5 * (((size) + 15) >> 4))
/**
* \brief Get buffer size to hold RSA public key elements.
*
* This macro returns the length (in bytes) of the buffer needed to
* receive the elements of a RSA public key, as generated by one of
* the `br_rsa_*_keygen()` functions. If the provided size is a constant
* expression, then the whole macro evaluates to a constant expression.
*
* \param size target key size (modulus size, in bits)
* \return the length of the public key buffer, in bytes.
*/
#define BR_RSA_KBUF_PUB_SIZE(size) (4 + (((size) + 7) >> 3))
/**
* \brief Type for RSA key pair generator implementation.
*
* This function generates a new RSA key pair whose modulus has bit
* length `size` bits. The private key elements are written in the
* `kbuf_priv` buffer, and pointer values and length fields to these
* elements are populated in the provided private key structure `sk`.
* Similarly, the public key elements are written in `kbuf_pub`, with
* pointers and lengths set in `pk`.
*
* If `pk` is `NULL`, then `kbuf_pub` may be `NULL`, and only the
* private key is set.
*
* If `pubexp` is not zero, then its value will be used as public
* exponent. Valid RSA public exponent values are odd integers
* greater than 1. If `pubexp` is zero, then the public exponent will
* have value 3.
*
* The provided PRNG (`rng_ctx`) must have already been initialized
* and seeded.
*
* Returned value is 1 on success, 0 on error. An error is reported
* if the requested range is outside of the supported key sizes, or
* if an invalid non-zero public exponent value is provided. Supported
* range starts at 512 bits, and up to an implementation-defined
* maximum (by default 4096 bits). Note that key sizes up to 768 bits
* have been broken in practice, and sizes lower than 2048 bits are
* usually considered to be weak and should not be used.
*
* \param rng_ctx source PRNG context (already initialized)
* \param sk RSA private key structure (destination)
* \param kbuf_priv buffer for private key elements
* \param pk RSA public key structure (destination), or `NULL`
* \param kbuf_pub buffer for public key elements, or `NULL`
* \param size target RSA modulus size (in bits)
* \param pubexp public exponent to use, or zero
* \return 1 on success, 0 on error (invalid parameters)
*/
typedef uint32_t (*br_rsa_keygen)(
const br_prng_class **rng_ctx,
br_rsa_private_key *sk, void *kbuf_priv,
br_rsa_public_key *pk, void *kbuf_pub,
unsigned size, uint32_t pubexp);
/**
* \brief RSA key pair generation with the "i15" engine.
*
* \see br_rsa_keygen
*
* \param rng_ctx source PRNG context (already initialized)
* \param sk RSA private key structure (destination)
* \param kbuf_priv buffer for private key elements
* \param pk RSA public key structure (destination), or `NULL`
* \param kbuf_pub buffer for public key elements, or `NULL`
* \param size target RSA modulus size (in bits)
* \param pubexp public exponent to use, or zero
* \return 1 on success, 0 on error (invalid parameters)
*/
uint32_t br_rsa_i15_keygen(
const br_prng_class **rng_ctx,
br_rsa_private_key *sk, void *kbuf_priv,
br_rsa_public_key *pk, void *kbuf_pub,
unsigned size, uint32_t pubexp);
/**
* \brief RSA key pair generation with the "i31" engine.
*
* \see br_rsa_keygen
*
* \param rng_ctx source PRNG context (already initialized)
* \param sk RSA private key structure (destination)
* \param kbuf_priv buffer for private key elements
* \param pk RSA public key structure (destination), or `NULL`
* \param kbuf_pub buffer for public key elements, or `NULL`
* \param size target RSA modulus size (in bits)
* \param pubexp public exponent to use, or zero
* \return 1 on success, 0 on error (invalid parameters)
*/
uint32_t br_rsa_i31_keygen(
const br_prng_class **rng_ctx,
br_rsa_private_key *sk, void *kbuf_priv,
br_rsa_public_key *pk, void *kbuf_pub,
unsigned size, uint32_t pubexp);
/**
* \brief RSA key pair generation with the "i62" engine.
*
* This function is defined only on architecture that offer a 64x64->128
* opcode. Use `br_rsa_i62_keygen_get()` to dynamically obtain a pointer
* to that function.
*
* \see br_rsa_keygen
*
* \param rng_ctx source PRNG context (already initialized)
* \param sk RSA private key structure (destination)
* \param kbuf_priv buffer for private key elements
* \param pk RSA public key structure (destination), or `NULL`
* \param kbuf_pub buffer for public key elements, or `NULL`
* \param size target RSA modulus size (in bits)
* \param pubexp public exponent to use, or zero
* \return 1 on success, 0 on error (invalid parameters)
*/
uint32_t br_rsa_i62_keygen(
const br_prng_class **rng_ctx,
br_rsa_private_key *sk, void *kbuf_priv,
br_rsa_public_key *pk, void *kbuf_pub,
unsigned size, uint32_t pubexp);
/**
* \brief Get the RSA "i62" implementation (key pair generation),
* if available.
*
* \return the implementation, or 0.
*/
br_rsa_keygen br_rsa_i62_keygen_get(void);
/**
* \brief Get "default" RSA implementation (key pair generation).
*
* This returns the preferred implementation of RSA (key pair generation)
* on the current system.
*
* \return the default implementation.
*/
br_rsa_keygen br_rsa_keygen_get_default(void);
/**
* \brief Type for a modulus computing function.
*
* Such a function computes the public modulus from the private key. The
* encoded modulus (unsigned big-endian) is written on `n`, and the size
* (in bytes) is returned. If `n` is `NULL`, then the size is returned but
* the modulus itself is not computed.
*
* If the key size exceeds an internal limit, 0 is returned.
*
* \param n destination buffer (or `NULL`).
* \param sk RSA private key.
* \return the modulus length (in bytes), or 0.
*/
typedef size_t (*br_rsa_compute_modulus)(void *n, const br_rsa_private_key *sk);
/**
* \brief Recompute RSA modulus ("i15" engine).
*
* \see br_rsa_compute_modulus
*
* \param n destination buffer (or `NULL`).
* \param sk RSA private key.
* \return the modulus length (in bytes), or 0.
*/
size_t br_rsa_i15_compute_modulus(void *n, const br_rsa_private_key *sk);
/**
* \brief Recompute RSA modulus ("i31" engine).
*
* \see br_rsa_compute_modulus
*
* \param n destination buffer (or `NULL`).
* \param sk RSA private key.
* \return the modulus length (in bytes), or 0.
*/
size_t br_rsa_i31_compute_modulus(void *n, const br_rsa_private_key *sk);
/**
* \brief Get "default" RSA implementation (recompute modulus).
*
* This returns the preferred implementation of RSA (recompute modulus)
* on the current system.
*
* \return the default implementation.
*/
br_rsa_compute_modulus br_rsa_compute_modulus_get_default(void);
/**
* \brief Type for a public exponent computing function.
*
* Such a function recomputes the public exponent from the private key.
* 0 is returned if any of the following occurs:
*
* - Either `p` or `q` is not equal to 3 modulo 4.
*
* - The public exponent does not fit on 32 bits.
*
* - An internal limit is exceeded.
*
* - The private key is invalid in some way.
*
* For all private keys produced by the key generator functions
* (`br_rsa_keygen` type), this function succeeds and returns the true
* public exponent. The public exponent is always an odd integer greater
* than 1.
*
* \return the public exponent, or 0.
*/
typedef uint32_t (*br_rsa_compute_pubexp)(const br_rsa_private_key *sk);
/**
* \brief Recompute RSA public exponent ("i15" engine).
*
* \see br_rsa_compute_pubexp
*
* \return the public exponent, or 0.
*/
uint32_t br_rsa_i15_compute_pubexp(const br_rsa_private_key *sk);
/**
* \brief Recompute RSA public exponent ("i31" engine).
*
* \see br_rsa_compute_pubexp
*
* \return the public exponent, or 0.
*/
uint32_t br_rsa_i31_compute_pubexp(const br_rsa_private_key *sk);
/**
* \brief Get "default" RSA implementation (recompute public exponent).
*
* This returns the preferred implementation of RSA (recompute public
* exponent) on the current system.
*
* \return the default implementation.
*/
br_rsa_compute_pubexp br_rsa_compute_pubexp_get_default(void);
/**
* \brief Type for a private exponent computing function.
*
* An RSA private key (`br_rsa_private_key`) contains two reduced
* private exponents, which are sufficient to perform private key
* operations. However, standard encoding formats for RSA private keys
* require also a copy of the complete private exponent (non-reduced),
* which this function recomputes.
*
* This function suceeds if all the following conditions hold:
*
* - Both private factors `p` and `q` are equal to 3 modulo 4.
*
* - The provided public exponent `pubexp` is correct, and, in particular,
* is odd, relatively prime to `p-1` and `q-1`, and greater than 1.
*
* - No internal storage limit is exceeded.
*
* For all private keys produced by the key generator functions
* (`br_rsa_keygen` type), this function succeeds. Note that the API
* restricts the public exponent to a maximum size of 32 bits.
*
* The encoded private exponent is written in `d` (unsigned big-endian
* convention), and the length (in bytes) is returned. If `d` is `NULL`,
* then the exponent is not written anywhere, but the length is still
* returned. On error, 0 is returned.
*
* Not all error conditions are detected when `d` is `NULL`; therefore, the
* returned value shall be checked also when actually producing the value.
*
* \param d destination buffer (or `NULL`).
* \param sk RSA private key.
* \param pubexp the public exponent.
* \return the private exponent length (in bytes), or 0.
*/
typedef size_t (*br_rsa_compute_privexp)(void *d,
const br_rsa_private_key *sk, uint32_t pubexp);
/**
* \brief Recompute RSA private exponent ("i15" engine).
*
* \see br_rsa_compute_privexp
*
* \param d destination buffer (or `NULL`).
* \param sk RSA private key.
* \param pubexp the public exponent.
* \return the private exponent length (in bytes), or 0.
*/
size_t br_rsa_i15_compute_privexp(void *d,
const br_rsa_private_key *sk, uint32_t pubexp);
/**
* \brief Recompute RSA private exponent ("i31" engine).
*
* \see br_rsa_compute_privexp
*
* \param d destination buffer (or `NULL`).
* \param sk RSA private key.
* \param pubexp the public exponent.
* \return the private exponent length (in bytes), or 0.
*/
size_t br_rsa_i31_compute_privexp(void *d,
const br_rsa_private_key *sk, uint32_t pubexp);
/**
* \brief Get "default" RSA implementation (recompute private exponent).
*
* This returns the preferred implementation of RSA (recompute private
* exponent) on the current system.
*
* \return the default implementation.
*/
br_rsa_compute_privexp br_rsa_compute_privexp_get_default(void);
#ifdef __cplusplus
}
#endif
#endif