dzeikei

# Convert base64 string from Google to a pem file
openssl enc -base64 -d -in publickey.base64 -A | openssl rsa -inform DER -pubin > public.pem
 
# Decode base64 signature to binary
openssl base64 -d -A -in signature.txt -out signature.sha1
 
# Verify signature
openssl dgst -sha1 -verify public.pem -signature signature.sha1 receipt.json

rob-murray

#1 Generate Public & Private Keypair
 
#2 Create receipt.json - eg below - careful with line-endings, etc if line breaks
 
#3 Create signature & Encode
openssl dgst -binary -sha1 -sign private.pem receipt.json | openssl base64 > signature.txt
 
#4 Verify using OpenSSL & public key
openssl base64 -d -in signature.txt -out signature.sha1 | openssl dgst -sha1 -verify public.pem -signature signature.sha1 receipt.json