Hi, When printing the contents of a PEM ECC keypair file for the secp160k1/r1/r2 curves, OpenSSL says the private key is 161 bits: $ openssl ecparam -name secp160k1 -genkey -out test.pem $ openssl ec -in test.pem -text -noout read EC key Private-Key: (161 bit) priv: 77:76:fb:ae:7a:0b:97:98:aa:c0:70:7d:af:28:14: 6d:4f:03:d9:b5 pub: 04:9b:98:38:4a:d0:e4:22:a2:3f:80:ce:02:90:02: d3:35:51:dc:8f:7b:5e:30:7d:2d:5e:98:6f:4b:9b: 4b:c8:01:1c:2d:ce:39:37:04:c5:61 ASN1 OID: secp160k1 However, following "priv:", there are only 20 bytes (160 bits). Why is this? When printing the keypair for other curves, the number of bytes after "priv:" seem to always be the same or higher than the number of bits shown after "Private-Key:". Thanks in advance, Frode