size of the decoded data is stored in *OUTLEN. OUTLEN may be NULL,
if the caller is not interested in the decoded length. *OUT may be
NULL to indicate an out of memory error, in which case *OUTLEN
size of the decoded data is stored in *OUTLEN. OUTLEN may be NULL,
if the caller is not interested in the decoded length. *OUT may be
NULL to indicate an out of memory error, in which case *OUTLEN