Merge pull request #28 from zgiber/fix-iat-validation

use GetTime when validating "iat" claim

.travis.yml

diff --git a/.travis.yml b/.travis.yml
index 64e44fa..6f70d93 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,8 @@
 language: go
 
 go:
-  - 1.5
   - 1.6
+  - 1.7
   - tip
 
 sudo: false
@@ -11,4 +11,4 @@
   - go get -u github.com/golang/lint/golint
 
 script:
-  - ./_test.sh
\ No newline at end of file
+  - ./_test.sh

README.md

diff --git a/README.md b/README.md
index 52e31d7..44edd54 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,9 @@
 
 The docs can be found at [godoc.org] [docs], as usual.
 
+A gopkg.in mirror can be found at https://gopkg.in/jose.v1, thanks to
+@zia-newversion. (For context, see #30.) 
+
 ### [JWS RFC][jws]
 ### [JWE RFC][jwe]
 ### [JWT RFC][jwt]

jwt/jwt.go

diff --git a/jwt/jwt.go b/jwt/jwt.go
index d29c43a..feb1712 100644
--- a/jwt/jwt.go
+++ b/jwt/jwt.go
@@ -59,9 +59,10 @@
 		j.Claims().Get("sub") != sub {
 		return ErrInvalidSUBClaim
 	}
-	if iat, ok := v.Expected.IssuedAt(); ok &&
-		j.Claims().Get("iat") != iat {
-		return ErrInvalidIATClaim
+	if iat, ok := v.Expected.IssuedAt(); ok {
+		if t, ok := j.Claims().GetTime("iat"); !t.Equal(iat) || !ok {
+			return ErrInvalidIATClaim
+		}
 	}
 	if jti, ok := v.Expected.JWTID(); ok &&
 		j.Claims().Get("jti") != jti {