Implement VerifySignedData() for ECDSA, RSA PKCS#1 and RSA PSS.

net/data/verify_signed_data_unittest/rsa-pkcs1-sha256.pem

Index: net/data/verify_signed_data_unittest/rsa-pkcs1-sha256.pem
diff --git a/net/data/verify_signed_data_unittest/rsa-pkcs1-sha256.pem b/net/data/verify_signed_data_unittest/rsa-pkcs1-sha256.pem
new file mode 100644
index 0000000000000000000000000000000000000000..8509111ea9b5a1d62c54e9c734d51c494817c2ed
--- /dev/null
+++ b/net/data/verify_signed_data_unittest/rsa-pkcs1-sha256.pem
@@ -0,0 +1,86 @@
+This test data was produced by creating a self-signed EC cert using OpenSSL,
+and then extracting the relevant fields.
+
+It uses RSA PKCS#1 v1.5 with SHA-256 and a 1024-bit key.
+
+(1) Generate self-signed certificate
+
+  openssl genrsa -out rsa_key.pem 1024
+  openssl req -new -key rsa_key.pem -x509 -nodes -days 365 -out cert.pem
+
+(2) Extract public key
+
+  openssl x509 -in cert.pem -pubkey -noout > pubkey.pem
+  cat pubkey.pem
+
+(3) Extract signed data (tbsCertificate)
+
+  openssl asn1parse -in cert.pem -out tbs -noout -strparse 4
+  base64 tbs
+
+(4) Extract signature algorithm
+
+  # Find the offset of the signature algorithm near the end (491 in this case)
+  openssl asn1parse -in cert.pem
+
+  openssl asn1parse -in cert.pem -out alg -noout -strparse 491
+  base64 alg
+
+(5) Extract the signature
+
+  # Find the final offset of BIT STRING (506 in this case)
+  openssl asn1parse -in cert.pem
+
+  openssl asn1parse -in cert.pem -out sig -noout -strparse 506
+  base64 sig
+
+
+
+-----BEGIN PUBLIC KEY-----
+MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCqR+B2Mj1irNp1JnY2zQIQRQPz7ybs6mUjHT3
+hf5APyaig2u6fBPThqxssgg0YviqIj/70hVK/JXcqP1zgR5AhsA0agnwAjfB/ow4EH+3HEYV52q
+pxN98pUxC+1l2hgVtn8xCS/JGyjK+6dv+lZw3ixJoX2RjVtdJ4/cn318EhhQIDAQAB
+-----END PUBLIC KEY-----
+
+$ openssl asn1parse -i < [PUBLIC KEY]
+    0:d=0  hl=3 l= 159 cons: SEQUENCE          
+    3:d=1  hl=2 l=  13 cons:  SEQUENCE          
+    5:d=2  hl=2 l=   9 prim:   OBJECT            :rsaEncryption
+   16:d=2  hl=2 l=   0 prim:   NULL              
+   18:d=1  hl=3 l= 141 prim:  BIT STRING        
+
+
+
+-----BEGIN ALGORITHM-----
+MA0GCSqGSIb3DQEBCwUA
+-----END ALGORITHM-----
+
+$ openssl asn1parse -i < [ALGORITHM]
+    0:d=0  hl=2 l=  13 cons: SEQUENCE          
+    2:d=1  hl=2 l=   9 prim:  OBJECT            :sha256WithRSAEncryption
+   13:d=1  hl=2 l=   0 prim:  NULL              
+
+
+
+-----BEGIN DATA-----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+-----END DATA-----
+
+
+
+-----BEGIN SIGNATURE-----
+A4GBADrHSmFSJw/Gv7hs5PNzpaJwAri/sitarIZfzN/SjR+n8L8yeTEoiDb1+BkxlFvXvPHTaOK
+oO3WlslNNOxh1W5/JkYYGOUkCcyIjnln6qS560imcr3VNjomT/M8M2Iss+rJiKau1TRuaP7H8i6
++Gqf3saGdr8/LnvFAdNQvkalQt
+-----END SIGNATURE-----
+
+$ openssl asn1parse -i < [SIGNATURE]
+    0:d=0  hl=3 l= 129 prim: BIT STRING