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Diffstat (limited to 'doc/man3/RSA_public_encrypt.pod')
| -rw-r--r-- | doc/man3/RSA_public_encrypt.pod | 38 |
1 files changed, 26 insertions, 12 deletions
diff --git a/doc/man3/RSA_public_encrypt.pod b/doc/man3/RSA_public_encrypt.pod index 91c176e24c52..d91c6884b1d5 100644 --- a/doc/man3/RSA_public_encrypt.pod +++ b/doc/man3/RSA_public_encrypt.pod @@ -8,10 +8,10 @@ RSA_public_encrypt, RSA_private_decrypt - RSA public key cryptography #include <openssl/rsa.h> - int RSA_public_encrypt(int flen, unsigned char *from, + int RSA_public_encrypt(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding); - int RSA_private_decrypt(int flen, unsigned char *from, + int RSA_private_decrypt(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding); =head1 DESCRIPTION @@ -27,6 +27,8 @@ B<padding> denotes one of the following modes: =item RSA_PKCS1_PADDING PKCS #1 v1.5 padding. This currently is the most widely used mode. +However, it is highly recommended to use RSA_PKCS1_OAEP_PADDING in +new applications. SEE WARNING BELOW. =item RSA_PKCS1_OAEP_PADDING @@ -46,23 +48,35 @@ Encrypting user data directly with RSA is insecure. =back -B<flen> must be less than RSA_size(B<rsa>) - 11 for the PKCS #1 v1.5 -based padding modes, less than RSA_size(B<rsa>) - 41 for +B<flen> must not be more than RSA_size(B<rsa>) - 11 for the PKCS #1 v1.5 +based padding modes, not more than RSA_size(B<rsa>) - 42 for RSA_PKCS1_OAEP_PADDING and exactly RSA_size(B<rsa>) for RSA_NO_PADDING. -The random number generator must be seeded prior to calling -RSA_public_encrypt(). +When a padding mode other than RSA_NO_PADDING is in use, then +RSA_public_encrypt() will include some random bytes into the ciphertext +and therefore the ciphertext will be different each time, even if the +plaintext and the public key are exactly identical. +The returned ciphertext in B<to> will always be zero padded to exactly +RSA_size(B<rsa>) bytes. +B<to> and B<from> may overlap. RSA_private_decrypt() decrypts the B<flen> bytes at B<from> using the -private key B<rsa> and stores the plaintext in B<to>. B<to> must point -to a memory section large enough to hold the decrypted data (which is -smaller than RSA_size(B<rsa>)). B<padding> is the padding mode that -was used to encrypt the data. +private key B<rsa> and stores the plaintext in B<to>. B<flen> should +be equal to RSA_size(B<rsa>) but may be smaller, when leading zero +bytes are in the ciphertext. Those are not important and may be removed, +but RSA_public_encrypt() does not do that. B<to> must point +to a memory section large enough to hold the maximal possible decrypted +data (which is equal to RSA_size(B<rsa>) for RSA_NO_PADDING, +RSA_size(B<rsa>) - 11 for the PKCS #1 v1.5 based padding modes and +RSA_size(B<rsa>) - 42 for RSA_PKCS1_OAEP_PADDING). +B<padding> is the padding mode that was used to encrypt the data. +B<to> and B<from> may overlap. =head1 RETURN VALUES RSA_public_encrypt() returns the size of the encrypted data (i.e., RSA_size(B<rsa>)). RSA_private_decrypt() returns the size of the -recovered plaintext. +recovered plaintext. A return value of 0 is not an error and +means only that the plaintext was empty. On error, -1 is returned; the error codes can be obtained by L<ERR_get_error(3)>. @@ -85,7 +99,7 @@ L<RSA_size(3)> =head1 COPYRIGHT -Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. +Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved. Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy |