(Tcl) ECDSA Sign Data and Verify Signature

Demonstrates using the Elliptic Curve Digital Signature Algorithm to hash data and sign it. Also demonstrates how to verify the ECDSA signature.

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load ./chilkat.dll

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

# To create an ECDSA signature, the data first needs to be hashed.  Then the hash
# is signed.

# Use Chilkat Crypt2 to generate a hash for any of the following
# hash algorithms: SHA256, SHA384, SHA512, SHA1, MD5, MD2, HAVAL, RIPEMD128/160/256/320

set crypt [new_CkCrypt2]

CkCrypt2_put_HashAlgorithm $crypt "SHA256"
CkCrypt2_put_Charset $crypt "utf-8"
CkCrypt2_put_EncodingMode $crypt "base64"

# Hash a string.
set hash1 [CkCrypt2_hashStringENC $crypt "The quick brown fox jumps over the lazy dog"]
puts "hash1 = $hash1"

# Or hash a file..
set hash2 [CkCrypt2_hashFileENC $crypt "qa_data/hamlet.xml"]
puts "hash2 = $hash2"

# (The Crypt2 API provides many other ways to hash data..)

# -----------------------------------------------------------
# An ECDSA private key is used for signing.  The public key is for signature verification.
# Load our ECC private key.
# Our private key file contains this:

# 	// -----BEGIN PRIVATE KEY-----
# 	MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg3J8q/24D1sEKGdP9
# 	72MGYElLGpw/a56Y3t6pfON3uhShRANCAATlSmoizyhAwoYZAOuFBATl07/1RR54
# 	a1Dzfm16grxJe666AGKR+bSs24hk7TEpaeCTvT8YOOM3l+xKFg7zq6Q9
# 	-----END PRIVATE KEY-----

set privKey [new_CkPrivateKey]

set success [CkPrivateKey_LoadPemFile $privKey "qa_data/ecc/secp256r1-key-pkcs8.pem"]
if {$success != 1} then {
    puts [CkPrivateKey_lastErrorText $privKey]
    delete_CkCrypt2 $crypt
    delete_CkPrivateKey $privKey
    exit
}

# We'll need a PRNG source for random number generation.
# Use Chilkat's PRNG (for the Fortuna PRNG algorithm).
set prng [new_CkPrng]

# Sign the hash..
set ecdsa [new_CkEcc]

set ecdsaSigBase64 [CkEcc_signHashENC $ecdsa $hash1 "base64" $privKey $prng]
if {[CkEcc_get_LastMethodSuccess $ecdsa] != 1} then {
    puts [CkEcc_lastErrorText $ecdsa]
    delete_CkCrypt2 $crypt
    delete_CkPrivateKey $privKey
    delete_CkPrng $prng
    delete_CkEcc $ecdsa
    exit
}

puts "ECDSA signature = $ecdsaSigBase64"

# -----------------------------------------------------------
# Now let's verify the signature using the public key.

set pubKey [new_CkPublicKey]

set success [CkPublicKey_LoadFromFile $pubKey "qa_data/ecc/secp256r1-pubkey.pem"]
if {$success != 1} then {
    puts [CkPublicKey_lastErrorText $pubKey]
    delete_CkCrypt2 $crypt
    delete_CkPrivateKey $privKey
    delete_CkPrng $prng
    delete_CkEcc $ecdsa
    delete_CkPublicKey $pubKey
    exit
}

set result [CkEcc_VerifyHashENC $ecdsa $hash1 $ecdsaSigBase64 "base64" $pubKey]
if {$result == 1} then {
    puts "Signature is valid."
    delete_CkCrypt2 $crypt
    delete_CkPrivateKey $privKey
    delete_CkPrng $prng
    delete_CkEcc $ecdsa
    delete_CkPublicKey $pubKey
    exit
}

if {$result == 0} then {
    puts "Signature is invalid."
    delete_CkCrypt2 $crypt
    delete_CkPrivateKey $privKey
    delete_CkPrng $prng
    delete_CkEcc $ecdsa
    delete_CkPublicKey $pubKey
    exit
}

if {$result < 0} then {
    puts [CkEcc_lastErrorText $ecdsa]
    puts "The VerifyHashENC method call failed."
    delete_CkCrypt2 $crypt
    delete_CkPrivateKey $privKey
    delete_CkPrng $prng
    delete_CkEcc $ecdsa
    delete_CkPublicKey $pubKey
    exit
}


delete_CkCrypt2 $crypt
delete_CkPrivateKey $privKey
delete_CkPrng $prng
delete_CkEcc $ecdsa
delete_CkPublicKey $pubKey