NAME

RSA_size, RSA_bits — get the RSA modulus size

SYNOPSIS

library “libcrypto”
#include <openssl/rsa.h>

int
RSA_size(const RSA *rsa);

int
RSA_bits(const RSA *rsa);

DESCRIPTION

RSA_size() returns the RSA modulus size in bytes. It can be used to determine how much memory must be allocated for an RSA encrypted value.

RSA_bits() returns the number of significant bits.

rsa and rsa->n must not be NULL.

RETURN VALUES

The size.

SEE ALSO

BN_num_bits(3), RSA_get0_key(3), RSA_new(3), RSA_security_bits(3)

HISTORY

RSA_size() first appeared in SSLeay 0.4.4 and has been available since OpenBSD 2.4.

RSA_bits() first appeared in OpenSSL 1.1.0 and has been available since OpenBSD 6.3.