(Tcl) Generate ECDSA Key and Get Details as XML

Demonstrates how to generate an ECC key and gets the parts as XML.

Chilkat Tcl Extension Downloads Chilkat Tcl Extension Downloads

load ./chilkat.dll

# This requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

set ecc [new_CkEcc]

# Generate a random ECC private key on the secp256k1 curve.
# Chilkat also supports other curves, such as secp384r1, secp521r1, and secp256r1.

# Create a Fortuna PRNG and seed it with system entropy.
# This will be our source of random data for generating the ECC private key.
set fortuna [new_CkPrng]

set entropy [CkPrng_getEntropy $fortuna 32 "base64"]
set success [CkPrng_AddEntropy $fortuna $entropy "base64"]

# privKey is a CkPrivateKey
set privKey [CkEcc_GenEccKey $ecc "secp256k1" $fortuna]
if {[CkEcc_get_LastMethodSuccess $ecc] != 1} then {
    puts [CkEcc_lastErrorText $ecc]
    delete_CkEcc $ecc
    delete_CkPrng $fortuna
    exit
}

# An EC private key has this ASN.1
# ECPrivateKey ::= SEQUENCE {
#     version        INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
#     privateKey     OCTET STRING,
#     parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
#     publicKey  [1] BIT STRING OPTIONAL (This is the ANSI X9.63 public key format.)

set asn [new_CkAsn]

set success [CkAsn_LoadEncoded $asn [CkPrivateKey_getPkcs1ENC $privKey "base64"] "base64"]
if {$success != 1} then {
    puts [CkAsn_lastErrorText $asn]
    delete_CkEcc $ecc
    delete_CkPrng $fortuna
    delete_CkAsn $asn
    exit
}

set xml [new_CkXml]

CkXml_LoadXml $xml [CkAsn_asnToXml $asn]

puts [CkXml_getXml $xml]

# The XML looks like this:
# <?xml version="1.0" encoding="utf-8" ?>
# <sequence>
#     <int>01</int>
#     <octets>JgJvBG+3wletkJab8iXAkpz0O8/AgWZSpkYVcB7SpnU=</octets>
#     <contextSpecific tag="0" constructed="1">
#         <oid>1.3.132.0.10</oid>
#     </contextSpecific>
# </sequence>

# The 32-byte private key is in the octets..
# Get it as hex.
set crypt [new_CkCrypt2]

set privKeyHex [CkCrypt2_reEncode $crypt [CkXml_getChildContent $xml "octets"] "base64" "hex"]

puts "EC private key as hex = $privKeyHex"

delete_CkPrivateKey $privKey


delete_CkEcc $ecc
delete_CkPrng $fortuna
delete_CkAsn $asn
delete_CkXml $xml
delete_CkCrypt2 $crypt