diff --git a/.travis.yml b/.travis.yml
index 13211f736311523625f9aecd56ebca989a26e030..c1d545c548daaadb9255895722fb9ff7d2178f9d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,10 +20,6 @@ env:
   global:
     - secure: "U2U1AmkU4NJBgKR/uUAebQY87cNL0+1JHjnLOmmXwxYYyj5ralWb1aSuSH3qSXiT93qLBmtaUkuv9fberHVqrbAeVlztVdUsKAq7JMQH+M99iFkC9UiRMqHmtjWJ0ok4COD1sRYixxi21wb/JrMe3M1iL4QJVS61iltjHhVdM64="
 sudo: false
-addons:
-  apt:
-    packages:
-    - libgmp3-dev
 notifications:
   webhooks:
     urls:
diff --git a/Makefile b/Makefile
index 41cbc1ce6cf71c51faf2850b8e48284b4ad14ee1..44723a4df8c6d55524016f76ce4776cacebeb037 100644
--- a/Makefile
+++ b/Makefile
@@ -10,7 +10,7 @@
 
 GOBIN = build/bin
 
-CROSSDEPS = https://gmplib.org/download/gmp/gmp-6.0.0a.tar.bz2
+MODE ?= default
 GO ?= latest
 
 geth:
@@ -26,32 +26,51 @@ geth-linux: xgo geth-linux-arm geth-linux-386 geth-linux-amd64
 	@echo "Linux cross compilation done:"
 	@ls -l $(GOBIN)/geth-linux-*
 
-geth-linux-arm: xgo
-	build/env.sh $(GOBIN)/xgo --go=$(GO) --dest=$(GOBIN) --deps=$(CROSSDEPS) --targets=linux/arm -v $(shell build/flags.sh) ./cmd/geth
-	@echo "Linux ARM cross compilation done:"
-	@ls -l $(GOBIN)/geth-linux-* | grep arm
-
 geth-linux-386: xgo
-	build/env.sh $(GOBIN)/xgo --go=$(GO) --dest=$(GOBIN) --deps=$(CROSSDEPS) --targets=linux/386 -v $(shell build/flags.sh) ./cmd/geth
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=linux/386 -v $(shell build/flags.sh) ./cmd/geth
 	@echo "Linux 386 cross compilation done:"
 	@ls -l $(GOBIN)/geth-linux-* | grep 386
 
 geth-linux-amd64: xgo
-	build/env.sh $(GOBIN)/xgo --go=$(GO) --dest=$(GOBIN) --deps=$(CROSSDEPS) --targets=linux/amd64 -v $(shell build/flags.sh) ./cmd/geth
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=linux/amd64 -v $(shell build/flags.sh) ./cmd/geth
 	@echo "Linux amd64 cross compilation done:"
 	@ls -l $(GOBIN)/geth-linux-* | grep amd64
 
-geth-darwin: xgo geth-darwin-386 geth-darwin-amd64
+geth-linux-arm: geth-linux-arm-5 geth-linux-arm-6 geth-linux-arm-7 geth-linux-arm64
+	@echo "Linux ARM cross compilation done:"
+	@ls -l $(GOBIN)/geth-linux-* | grep arm
+
+geth-linux-arm-5: xgo
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=linux/arm-5 -v $(shell build/flags.sh) ./cmd/geth
+	@echo "Linux ARMv5 cross compilation done:"
+	@ls -l $(GOBIN)/geth-linux-* | grep arm-5
+
+geth-linux-arm-6: xgo
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=linux/arm-6 -v $(shell build/flags.sh) ./cmd/geth
+	@echo "Linux ARMv6 cross compilation done:"
+	@ls -l $(GOBIN)/geth-linux-* | grep arm-6
+
+geth-linux-arm-7: xgo
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=linux/arm-7 -v $(shell build/flags.sh) ./cmd/geth
+	@echo "Linux ARMv7 cross compilation done:"
+	@ls -l $(GOBIN)/geth-linux-* | grep arm-7
+
+geth-linux-arm64: xgo
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=linux/arm64 -v $(shell build/flags.sh) ./cmd/geth
+	@echo "Linux ARM64 cross compilation done:"
+	@ls -l $(GOBIN)/geth-linux-* | grep arm64
+
+geth-darwin: geth-darwin-386 geth-darwin-amd64
 	@echo "Darwin cross compilation done:"
 	@ls -l $(GOBIN)/geth-darwin-*
 
 geth-darwin-386: xgo
-	build/env.sh $(GOBIN)/xgo --go=$(GO) --dest=$(GOBIN) --deps=$(CROSSDEPS) --targets=darwin/386 -v $(shell build/flags.sh) ./cmd/geth
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=darwin/386 -v $(shell build/flags.sh) ./cmd/geth
 	@echo "Darwin 386 cross compilation done:"
 	@ls -l $(GOBIN)/geth-darwin-* | grep 386
 
 geth-darwin-amd64: xgo
-	build/env.sh $(GOBIN)/xgo --go=$(GO) --dest=$(GOBIN) --deps=$(CROSSDEPS) --targets=darwin/amd64 -v $(shell build/flags.sh) ./cmd/geth
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=darwin/amd64 -v $(shell build/flags.sh) ./cmd/geth
 	@echo "Darwin amd64 cross compilation done:"
 	@ls -l $(GOBIN)/geth-darwin-* | grep amd64
 
@@ -60,28 +79,33 @@ geth-windows: xgo geth-windows-386 geth-windows-amd64
 	@ls -l $(GOBIN)/geth-windows-*
 
 geth-windows-386: xgo
-	build/env.sh $(GOBIN)/xgo --go=$(GO) --dest=$(GOBIN) --deps=$(CROSSDEPS) --targets=windows/386 -v $(shell build/flags.sh) ./cmd/geth
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=windows/386 -v $(shell build/flags.sh) ./cmd/geth
 	@echo "Windows 386 cross compilation done:"
 	@ls -l $(GOBIN)/geth-windows-* | grep 386
 
 geth-windows-amd64: xgo
-	build/env.sh $(GOBIN)/xgo --go=$(GO) --dest=$(GOBIN) --deps=$(CROSSDEPS) --targets=windows/amd64 -v $(shell build/flags.sh) ./cmd/geth
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=windows/amd64 -v $(shell build/flags.sh) ./cmd/geth
 	@echo "Windows amd64 cross compilation done:"
 	@ls -l $(GOBIN)/geth-windows-* | grep amd64
 
-geth-android: xgo geth-android-16 geth-android-21
+geth-android: xgo
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=android/* -v $(shell build/flags.sh) ./cmd/geth
 	@echo "Android cross compilation done:"
 	@ls -l $(GOBIN)/geth-android-*
 
-geth-android-16: xgo
-	build/env.sh $(GOBIN)/xgo --go=$(GO) --dest=$(GOBIN) --deps=$(CROSSDEPS) --targets=android-16/* -v $(shell build/flags.sh) ./cmd/geth
-	@echo "Android 16 cross compilation done:"
-	@ls -l $(GOBIN)/geth-android-16-*
+geth-ios: geth-ios-arm-7 geth-ios-arm64
+	@echo "iOS cross compilation done:"
+	@ls -l $(GOBIN)/geth-ios-*
+
+geth-ios-arm-7: xgo
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=ios/arm-7 -v $(shell build/flags.sh) ./cmd/geth
+	@echo "iOS ARMv7 cross compilation done:"
+	@ls -l $(GOBIN)/geth-ios-* | grep arm-7
 
-geth-android-21: xgo
-	build/env.sh $(GOBIN)/xgo --go=$(GO) --dest=$(GOBIN) --deps=$(CROSSDEPS) --targets=android-21/* -v $(shell build/flags.sh) ./cmd/geth
-	@echo "Android 21 cross compilation done:"
-	@ls -l $(GOBIN)/geth-android-21-*
+geth-ios-arm64: xgo
+	build/env.sh $(GOBIN)/xgo --go=$(GO) --buildmode=$(MODE) --dest=$(GOBIN) --targets=ios-7.0/arm64 -v $(shell build/flags.sh) ./cmd/geth
+	@echo "iOS ARM64 cross compilation done:"
+	@ls -l $(GOBIN)/geth-ios-* | grep arm64
 
 evm:
 	build/env.sh $(GOROOT)/bin/go install -v $(shell build/flags.sh) ./cmd/evm
diff --git a/README.md b/README.md
index 717e726e3476b00ab9496ebc4c21899e48970843..2d60e0564d34b8fc5eb6da1b7ba883367ae79855 100644
--- a/README.md
+++ b/README.md
@@ -30,7 +30,7 @@ For prerequisites and detailed build instructions please read the
 [Installation Instructions](https://github.com/ethereum/go-ethereum/wiki/Building-Ethereum)
 on the wiki.
 
-Building geth requires two external dependencies, Go and GMP.
+Building geth requires both a Go and a C compiler.
 You can install them using your favourite package manager.
 Once the dependencies are installed, run
 
diff --git a/crypto/secp256k1/README.md b/crypto/secp256k1/README.md
deleted file mode 100644
index 5a86147d4856306b8c40a28831fb444476d5ffec..0000000000000000000000000000000000000000
--- a/crypto/secp256k1/README.md
+++ /dev/null
@@ -1,25 +0,0 @@
-secp256k1-go
-=======
-
-golang secp256k1 library
-
-Implements cryptographic operations for the secp256k1 ECDSA curve used by Bitcoin.
-
-Installing
-===
-
-GMP library headers are required to build. On Debian-based systems, the package is called `libgmp-dev`.
-
-```
-sudo apt-get install libgmp-dev
-```
-
-Now compiles with cgo!
-
-Test
-===
-
-To run tests do
-```
-go tests
-```
\ No newline at end of file
diff --git a/crypto/secp256k1/secp256.go b/crypto/secp256k1/secp256.go
index 93f7f5143d1f34ba65fd29896ff3c320fe1a6a0a..83f2a5f26e32199ab9fe49d6dfd822f042c7b457 100644
--- a/crypto/secp256k1/secp256.go
+++ b/crypto/secp256k1/secp256.go
@@ -20,14 +20,8 @@ package secp256k1
 
 /*
 #cgo CFLAGS: -I./libsecp256k1
-#cgo darwin CFLAGS: -I/usr/local/include
-#cgo freebsd CFLAGS: -I/usr/local/include
-#cgo linux,arm CFLAGS: -I/usr/local/arm/include
-#cgo LDFLAGS: -lgmp
-#cgo darwin LDFLAGS: -L/usr/local/lib
-#cgo freebsd LDFLAGS: -L/usr/local/lib
-#cgo linux,arm LDFLAGS: -L/usr/local/arm/lib
-#define USE_NUM_GMP
+#cgo CFLAGS: -I./libsecp256k1/src/
+#define USE_NUM_NONE
 #define USE_FIELD_10X26
 #define USE_FIELD_INV_BUILTIN
 #define USE_SCALAR_8X32