Update the documentation of BN_hex2bn()

Reviewed-by: Kurt Roeckx <kurt@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>

1 files changed, 9 insertions, 7 deletions

diff --git a/doc/crypto/BN_bn2bin.pod b/doc/crypto/BN_bn2bin.pod
index b229da7b70..8098fd9df5 100644
--- a/doc/crypto/BN_bn2bin.pod
+++ b/doc/crypto/BN_bn2bin.pod
@@ -51,11 +51,12 @@ hexadecimal and decimal encoding of B<a> respectively. For negative
 numbers, the string is prefaced with a leading '-'. The string must be
 freed later using OPENSSL_free().
 
-BN_hex2bn() converts the string B<str> containing a hexadecimal number
-to a B<BIGNUM> and stores it in **B<bn>. If *B<bn> is NULL, a new
-B<BIGNUM> is created. If B<bn> is NULL, it only computes the number's
-length in hexadecimal digits. If the string starts with '-', the
-number is negative. BN_dec2bn() is the same using the decimal system.
+BN_hex2bn()takes as many characters as possible from the string B<str>,
+including the leading character '-' which means negative, to form a valid
+hexadecimal number representation and converts them to a B<BIGNUM> and
+stores it in **B<bn>. If *B<bn> is NULL, a new B<BIGNUM> is created. If
+B<bn> is NULL, it only computes the length of valid representation.
+BN_dec2bn() is the same using the decimal system.
 
 BN_print() and BN_print_fp() write the hexadecimal encoding of B<a>,
 with a leading '-' for negative numbers, to the B<BIO> or B<FILE>
@@ -84,8 +85,9 @@ BN_bn2binpad() returns the number of bytes written or -1 if the supplied
 buffer is too small.
 
 BN_bn2hex() and BN_bn2dec() return a null-terminated string, or NULL
-on error. BN_hex2bn() and BN_dec2bn() return the number's length in
-hexadecimal or decimal digits, and 0 on error.
+on error. BN_hex2bn() and BN_dec2bn() return the the length of valid
+representation in hexadecimal or decimal digits, and 0 on error, in which
+case no new B<BIGNUM> will be created.
 
 BN_print_fp() and BN_print() return 1 on success, 0 on write errors.