diff options
Diffstat (limited to 'nettle.texinfo')
| -rw-r--r-- | nettle.texinfo | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/nettle.texinfo b/nettle.texinfo index 431ae25a..f2a0f28b 100644 --- a/nettle.texinfo +++ b/nettle.texinfo @@ -3693,6 +3693,32 @@ point to a digest of size @code{MD5_DIGEST_SIZE}, @code{SHA1_DIGEST_SIZE}, or @code{SHA256_DIGEST_SIZE}, respectively. @end deftypefun +The RSA algorithm can also be used for encryption. RSA encryption uses +the public key @code{(n,e)} to compute the ciphertext @code{m^e mod n}. +The PKCS#1 padding scheme will use at least 8 random and non-zero +octets, using @var{m} of the form @code{[00 02 padding 00 plaintext]}. +It is required that @code{m < n}, and therefor the plaintext must be +smaller than the octet size of the modulo @code{n}, with some margin. + +The following function is used to encrypt a clear text message using RSA. +@deftypefun int rsa_encrypt (const struct rsa_public_key *@var{key}, void *@var{random_ctx}, nettle_random_func *@var{random}, size_t @var{length}, const uint8_t *@var{cleartext}, mpz_t @var{ciphertext}) +Returns 1 on success, 0 on failure. If the message is too long then this +will lead to a failure. +@end deftypefun +The following function is used to decrypt a cipher text message using RSA. +@deftypefun int rsa_decrypt (const struct rsa_private_key *@var{key}, size_t *@var{length}, uint8_t *@var{cleartext}, const mpz_t @var{ciphertext}) +Returns 1 on success, 0 on failure. Causes of failure include decryption +failing or the resulting message being to large. The message buffer +pointed to by @var{cleartext} must be of size *@var{length}. After +decryption, *@var{length} will be updated with the size of the +message. +@end deftypefun +There is also a timing resistant version of decryption that utilizes +randomized RSA blinding. +@deftypefun int rsa_decrypt_tr (const struct rsa_public_key *@var{pub}, const struct rsa_private_key *@var{key}, void *@var{random_ctx}, nettle_random_func *@var{random}, size_t *@var{length}, uint8_t *@var{message}, const mpz_t @var{ciphertext}) +Returns 1 on success, 0 on failure. +@end deftypefun + If you need to use the @acronym{RSA} trapdoor, the private key, in a way that isn't supported by the above functions Nettle also includes a function that computes @code{x^d mod n} and nothing more, using the |