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

net/data/verify_signed_data_unittest/rsa-pss-sha1-salt20.pem

Index: net/data/verify_signed_data_unittest/rsa-pss-sha1-salt20.pem
diff --git a/net/data/verify_signed_data_unittest/rsa-pss-sha1-salt20.pem b/net/data/verify_signed_data_unittest/rsa-pss-sha1-salt20.pem
new file mode 100644
index 0000000000000000000000000000000000000000..e56f0fe0cd4c095b564a490e5fd5ec9db8d6c776
--- /dev/null
+++ b/net/data/verify_signed_data_unittest/rsa-pss-sha1-salt20.pem
@@ -0,0 +1,53 @@
+The key, message, and signature come from Example 1.1 of:
+ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1-vec.zip (pss-vect.txt)
+
+(The algorithm DER was synthesized to match, and the signature enclosed in a BIT STRING).
+
+It uses an RSA key with modulus length of 1024 bits, PSS padding,
+SHA-1 as the digest, MGF1 with SHA-1, and salt length of 20.
+
+
+
+-----BEGIN PUBLIC KEY-----
+MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQClbkoOcBAXWJpRh9x+qEHRVvLsDjatUqRN/rH
+mH3rZkdjFEFb/7bFitMDyg6EqiKOU3/Umq3KRy7MHzqv84LHf1c2VCAltWyuLbfXWce9jd8CSHL
+I8Jwpw4lmOb/idGfEFrMLT8Ms18pKA4Thrb2TE7yLh4fINDOjP+yJJvZohNwIDAQAB
+-----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-----
+MA0GCSqGSIb3DQEBCjAA
+-----END ALGORITHM-----
+
+$ openssl asn1parse -i < [ALGORITHM]
+    0:d=0  hl=2 l=  13 cons: SEQUENCE          
+    2:d=1  hl=2 l=   9 prim:  OBJECT            :rsassaPss
+   13:d=1  hl=2 l=   0 cons:  SEQUENCE          
+
+
+
+-----BEGIN DATA-----
+zch9oiPXht87ReC7vHITJtHuKvgGzDFUdcxvDZxm4bYjcdRc4jkuGskoRMMQEC8Vag2NUsH0xAu
+jqmUJV4bLdpdXplY7qVj+0LzJhOi1F6PV9RWyO4pB50qoZ2k/kN+wYabobfqu5kRywA5fIJRXKc
+vr538Gznjgj0CY+6QfnWGTwDF+i2DUtghKy0LSnjgIo7w3LYXjMRcPy/fMctC3HClmSLOk0Q9BY
+pXQgHqmJcqydE/Z6o/SI8QlNwKYKL0WvgJUbxMP0uM7k20mduCK7RtzMYt1CgFn0A==
+-----END DATA-----
+
+
+
+-----BEGIN SIGNATURE-----
+A4GBAJB0MI+1mOlwGyKUOI5S+XH6rCtgpRRa8YXfUoe17SiH5Xzn/UTchjTkB8jg5DYLwibz7CJ
+/nZ5UY46NMfUFEhXfbrucL5V5qndZijj5FLW5wb2DxOL584Kg0Ko1Qv/uZZhKYBvGnrKN6yfcoS
+yCwtTD9mzVAPH/K5lNik4wy7M8
+-----END SIGNATURE-----
+
+$ openssl asn1parse -i < [SIGNATURE]
+    0:d=0  hl=3 l= 129 prim: BIT STRING