$NetBSD: RSA_private_encrypt.3,v 1.7 2013/02/12 19:52:13 christos Exp $

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Title "RSA_private_encrypt 3" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
RSA_private_encrypt, RSA_public_decrypt - low level signature operations libcrypto, -lcrypto Header "SYNOPSIS" .Vb 1 #include <openssl/rsa.h> \& int RSA_private_encrypt(int flen, unsigned char *from, unsigned char *to, RSA *rsa, int padding); \& int RSA_public_decrypt(int flen, unsigned char *from, unsigned char *to, RSA *rsa, int padding); .Ve Header "DESCRIPTION" These functions handle \s-1RSA\s0 signatures at a low level.

\fIRSA_private_encrypt() signs the flen bytes at from (usually a message digest with an algorithm identifier) using the private key \fBrsa and stores the signature in to. to must point to \fBRSA_size(rsa) bytes of memory.

\fBpadding denotes one of the following modes:

Item "RSA_PKCS1_PADDING" \s-1PKCS\s0 #1 v1.5 padding. This function does not handle the \fBalgorithmIdentifier specified in \s-1PKCS\s0 #1. When generating or verifying \s-1PKCS\s0 #1 signatures, RSA_sign\|(3) and RSA_verify\|(3) should be used. Item "RSA_NO_PADDING" Raw \s-1RSA\s0 signature. This mode should only be used to implement cryptographically sound padding modes in the application code. Signing user data directly with \s-1RSA\s0 is insecure.

\fIRSA_public_decrypt() recovers the message digest from the flen bytes long signature at from using the signer's public key \fBrsa. to must point to a memory section large enough to hold the message digest (which is smaller than RSA_size(rsa) - 11). padding is the padding mode that was used to sign the data.

Header "RETURN VALUES" \fIRSA_private_encrypt() returns the size of the signature (i.e., RSA_size(rsa)). RSA_public_decrypt() returns the size of the recovered message digest.

On error, -1 is returned; the error codes can be obtained by ERR_get_error\|(3).

Header "SEE ALSO" \fIERR_get_error\|(3), openssl_rsa\|(3), \fIRSA_sign\|(3), RSA_verify\|(3) Header "HISTORY" The padding argument was added in SSLeay 0.8. \s-1RSA_NO_PADDING\s0 is available since SSLeay 0.9.0.