BN_bn2bin.pod revision 325337
1=pod 2 3=head1 NAME 4 5BN_bn2bin, BN_bin2bn, BN_bn2hex, BN_bn2dec, BN_hex2bn, BN_dec2bn, 6BN_print, BN_print_fp, BN_bn2mpi, BN_mpi2bn - format conversions 7 8=head1 SYNOPSIS 9 10 #include <openssl/bn.h> 11 12 int BN_bn2bin(const BIGNUM *a, unsigned char *to); 13 BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret); 14 15 char *BN_bn2hex(const BIGNUM *a); 16 char *BN_bn2dec(const BIGNUM *a); 17 int BN_hex2bn(BIGNUM **a, const char *str); 18 int BN_dec2bn(BIGNUM **a, const char *str); 19 20 int BN_print(BIO *fp, const BIGNUM *a); 21 int BN_print_fp(FILE *fp, const BIGNUM *a); 22 23 int BN_bn2mpi(const BIGNUM *a, unsigned char *to); 24 BIGNUM *BN_mpi2bn(unsigned char *s, int len, BIGNUM *ret); 25 26=head1 DESCRIPTION 27 28BN_bn2bin() converts the absolute value of B<a> into big-endian form 29and stores it at B<to>. B<to> must point to BN_num_bytes(B<a>) bytes of 30memory. 31 32BN_bin2bn() converts the positive integer in big-endian form of length 33B<len> at B<s> into a B<BIGNUM> and places it in B<ret>. If B<ret> is 34NULL, a new B<BIGNUM> is created. 35 36BN_bn2hex() and BN_bn2dec() return printable strings containing the 37hexadecimal and decimal encoding of B<a> respectively. For negative 38numbers, the string is prefaced with a leading '-'. The string must be 39freed later using OPENSSL_free(). 40 41BN_hex2bn() converts the string B<str> containing a hexadecimal number 42to a B<BIGNUM> and stores it in **B<bn>. If *B<bn> is NULL, a new 43B<BIGNUM> is created. If B<bn> is NULL, it only computes the number's 44length in hexadecimal digits. If the string starts with '-', the 45number is negative. 46A "negative zero" is converted to zero. 47BN_dec2bn() is the same using the decimal system. 48 49BN_print() and BN_print_fp() write the hexadecimal encoding of B<a>, 50with a leading '-' for negative numbers, to the B<BIO> or B<FILE> 51B<fp>. 52 53BN_bn2mpi() and BN_mpi2bn() convert B<BIGNUM>s from and to a format 54that consists of the number's length in bytes represented as a 4-byte 55big-endian number, and the number itself in big-endian format, where 56the most significant bit signals a negative number (the representation 57of numbers with the MSB set is prefixed with null byte). 58 59BN_bn2mpi() stores the representation of B<a> at B<to>, where B<to> 60must be large enough to hold the result. The size can be determined by 61calling BN_bn2mpi(B<a>, NULL). 62 63BN_mpi2bn() converts the B<len> bytes long representation at B<s> to 64a B<BIGNUM> and stores it at B<ret>, or in a newly allocated B<BIGNUM> 65if B<ret> is NULL. 66 67=head1 RETURN VALUES 68 69BN_bn2bin() returns the length of the big-endian number placed at B<to>. 70BN_bin2bn() returns the B<BIGNUM>, NULL on error. 71 72BN_bn2hex() and BN_bn2dec() return a null-terminated string, or NULL 73on error. BN_hex2bn() and BN_dec2bn() return the number of characters 74used in parsing, or 0 on error, in which 75case no new B<BIGNUM> will be created. 76 77BN_print_fp() and BN_print() return 1 on success, 0 on write errors. 78 79BN_bn2mpi() returns the length of the representation. BN_mpi2bn() 80returns the B<BIGNUM>, and NULL on error. 81 82The error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>. 83 84=head1 SEE ALSO 85 86L<bn(3)|bn(3)>, L<ERR_get_error(3)|ERR_get_error(3)>, L<BN_zero(3)|BN_zero(3)>, 87L<ASN1_INTEGER_to_BN(3)|ASN1_INTEGER_to_BN(3)>, 88L<BN_num_bytes(3)|BN_num_bytes(3)> 89 90=head1 HISTORY 91 92BN_bn2bin(), BN_bin2bn(), BN_print_fp() and BN_print() are available 93in all versions of SSLeay and OpenSSL. 94 95BN_bn2hex(), BN_bn2dec(), BN_hex2bn(), BN_dec2bn(), BN_bn2mpi() and 96BN_mpi2bn() were added in SSLeay 0.9.0. 97 98=cut 99