Ubuntu Manpage: RSA_padding_add_PKCS1_type_1, RSA_padding_check_PKCS1_type

Provided by: libssl-doc_1.1.1-1ubuntu2.1~18.04.23_all

NAME

       RSA_padding_add_PKCS1_type_1, RSA_padding_check_PKCS1_type_1,
       RSA_padding_add_PKCS1_type_2, RSA_padding_check_PKCS1_type_2, RSA_padding_add_PKCS1_OAEP,
       RSA_padding_check_PKCS1_OAEP, RSA_padding_add_SSLv23, RSA_padding_check_SSLv23,
       RSA_padding_add_none, RSA_padding_check_none - asymmetric encryption padding

SYNOPSIS

        #include <openssl/rsa.h>

        int RSA_padding_add_PKCS1_type_1(unsigned char *to, int tlen,
                                         unsigned char *f, int fl);

        int RSA_padding_check_PKCS1_type_1(unsigned char *to, int tlen,
                                           unsigned char *f, int fl, int rsa_len);

        int RSA_padding_add_PKCS1_type_2(unsigned char *to, int tlen,
                                         unsigned char *f, int fl);

        int RSA_padding_check_PKCS1_type_2(unsigned char *to, int tlen,
                                           unsigned char *f, int fl, int rsa_len);

        int RSA_padding_add_PKCS1_OAEP(unsigned char *to, int tlen,
                                       unsigned char *f, int fl, unsigned char *p, int pl);

        int RSA_padding_check_PKCS1_OAEP(unsigned char *to, int tlen,
                                         unsigned char *f, int fl, int rsa_len,
                                         unsigned char *p, int pl);

        int RSA_padding_add_SSLv23(unsigned char *to, int tlen,
                                   unsigned char *f, int fl);

        int RSA_padding_check_SSLv23(unsigned char *to, int tlen,
                                     unsigned char *f, int fl, int rsa_len);

        int RSA_padding_add_none(unsigned char *to, int tlen,
                                 unsigned char *f, int fl);

        int RSA_padding_check_none(unsigned char *to, int tlen,
                                   unsigned char *f, int fl, int rsa_len);

DESCRIPTION

The RSA_padding_xxx_xxx() functions are called from the RSA encrypt, decrypt, sign and
verify functions. Normally they should not be called from application programs.

However, they can also be called directly to implement padding for other asymmetric
ciphers. RSA_padding_add_PKCS1_OAEP() and RSA_padding_check_PKCS1_OAEP() may be used in an
application combined with RSA_NO_PADDING in order to implement OAEP with an encoding
parameter.

RSA_padding_add_xxx() encodes fl bytes from f so as to fit into tlen bytes and stores the
result at to. An error occurs if fl does not meet the size requirements of the encoding
method.

The following encoding methods are implemented:

PKCS1_type_1
PKCS #1 v2.0 EMSA-PKCS1-v1_5 (PKCS #1 v1.5 block type 1); used for signatures

PKCS1_type_2
PKCS #1 v2.0 EME-PKCS1-v1_5 (PKCS #1 v1.5 block type 2)

PKCS1_OAEP
PKCS #1 v2.0 EME-OAEP

SSLv23
PKCS #1 EME-PKCS1-v1_5 with SSL-specific modification

none
simply copy the data

The random number generator must be seeded prior to calling RSA_padding_add_xxx().

RSA_padding_check_xxx() verifies that the fl bytes at f contain a valid encoding for a
rsa_len byte RSA key in the respective encoding method and stores the recovered data of at
most tlen bytes (for RSA_NO_PADDING: of size tlen) at to.

For RSA_padding_xxx_OAEP(), p points to the encoding parameter of length pl. p may be NULL
if pl is 0.

RETURN VALUES

       The RSA_padding_add_xxx() functions return 1 on success, 0 on error.  The
       RSA_padding_check_xxx() functions return the length of the recovered data, -1 on error.
       Error codes can be obtained by calling ERR_get_error(3).

WARNING

       The RSA_padding_check_PKCS1_type_2() padding check leaks timing information which can
       potentially be used to mount a Bleichenbacher padding oracle attack. This is an inherent
       weakness in the PKCS #1 v1.5 padding design. Prefer PKCS1_OAEP padding.

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