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author | Dr. Stephen Henson <steve@openssl.org> | 2015-02-19 14:35:43 +0000 |
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committer | Dr. Stephen Henson <steve@openssl.org> | 2015-02-21 00:45:06 +0000 |
commit | 146ca72cca3ab668d6bcb45b2a7f71bd9a8d06bb (patch) | |
tree | 90a3a891751b24de943cfb0f1443071c117fcf80 /doc/crypto/EC_GROUP_copy.pod | |
parent | 86f300d38540ead85543aee0cb30c32145931744 (diff) | |
download | openssl-146ca72cca3ab668d6bcb45b2a7f71bd9a8d06bb.zip openssl-146ca72cca3ab668d6bcb45b2a7f71bd9a8d06bb.tar.gz openssl-146ca72cca3ab668d6bcb45b2a7f71bd9a8d06bb.tar.bz2 |
Add additional EC documentation.
Reviewed-by: Matt Caswell <matt@openssl.org>
Diffstat (limited to 'doc/crypto/EC_GROUP_copy.pod')
-rw-r--r-- | doc/crypto/EC_GROUP_copy.pod | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/doc/crypto/EC_GROUP_copy.pod b/doc/crypto/EC_GROUP_copy.pod index 954af46..d8fb3dd 100644 --- a/doc/crypto/EC_GROUP_copy.pod +++ b/doc/crypto/EC_GROUP_copy.pod @@ -69,10 +69,18 @@ The functions EC_GROUP_set_curve_name and EC_GROUP_get_curve_name, set and get t (see L<EC_GROUP_new(3)|EC_GROUP_new(3)>). If a curve does not have a NID associated with it, then EC_GROUP_get_curve_name will return 0. -The asn1_flag value on a curve is used to determine whether there is a specific ASN1 OID to describe the curve or not. -If the asn1_flag is 1 then this is a named curve with an associated ASN1 OID. If not then asn1_flag is 0. The functions -EC_GROUP_get_asn1_flag and EC_GROUP_set_asn1_flag get and set the status of the asn1_flag for the curve. If set then -the curve_name must also be set. +The asn1_flag value is used to determine whether the curve encoding uses +explicit parameters or a named curve using an ASN1 OID: many applications only +support the latter form. If asn1_flag is B<OPENSSL_EC_NAMED_CURVE> then the +named curve form is used and the parameters must have a corresponding +named curve NID set. If asn1_flags is B<OPENSSL_EC_EXPLICIT_CURVE> the +parameters are explicitly encoded. The functions EC_GROUP_get_asn1_flag and +EC_GROUP_set_asn1_flag get and set the status of the asn1_flag for the curve. +Note: B<OPENSSL_EC_EXPLICIT_CURVE> was first added to OpenSSL 1.1.0, for +previous versions of OpenSSL the value 0 must be used instead. Before OpenSSL +1.1.0 the default form was to use explicit parameters (meaning that +applications would have to explicitly set the named curve form) in OpenSSL +1.1.0 and later the named curve form is the default. The point_coversion_form for a curve controls how EC_POINT data is encoded as ASN1 as defined in X9.62 (ECDSA). point_conversion_form_t is an enum defined as follows: |