Tcl

ECDSA Sign Data and Verify Signature

See more ECC Examples

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

load ./chilkat.dll

set success 0

# 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