Add full copy of mozilla/pkcs7 module as internal dependency

The full contents of the git repository @432b2356ecb...
was copied. Only go.mod was removed from it.

scep/pkcs7/.gitignore

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+# Compiled Object files, Static and Dynamic libs (Shared Objects)
+*.o
+*.a
+*.so
+
+# Folders
+_obj
+_test
+
+# Architecture specific extensions/prefixes
+*.[568vq]
+[568vq].out
+
+*.cgo1.go
+*.cgo2.c
+_cgo_defun.c
+_cgo_gotypes.go
+_cgo_export.*
+
+_testmain.go
+
+*.exe
+*.test
+*.prof

scep/pkcs7/.travis.yml

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+language: go
+go:
+    - "1.11"
+    - "1.12"
+    - "1.13"
+    - tip
+before_install:
+    - make gettools
+script:
+    - make

scep/pkcs7/LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2015 Andrew Smith
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+

scep/pkcs7/Makefile

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+all: vet staticcheck test
+
+test:
+	go test -covermode=count -coverprofile=coverage.out .
+
+showcoverage: test
+	go tool cover -html=coverage.out
+
+vet:
+	go vet .
+
+lint:
+	golint .
+
+staticcheck:
+	staticcheck .
+
+gettools:
+	go get -u honnef.co/go/tools/...
+	go get -u golang.org/x/lint/golint

scep/pkcs7/README.md

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+# pkcs7
+
+[![GoDoc](https://godoc.org/go.mozilla.org/pkcs7?status.svg)](https://godoc.org/go.mozilla.org/pkcs7)
+[![Build Status](https://travis-ci.org/mozilla-services/pkcs7.svg?branch=master)](https://travis-ci.org/mozilla-services/pkcs7)
+
+pkcs7 implements parsing and creating signed and enveloped messages.
+
+```go
+package main
+
+import (
+	"bytes"
+	"crypto/rsa"
+	"crypto/x509"
+	"encoding/pem"
+	"fmt"
+	"os"
+
+    "go.mozilla.org/pkcs7"
+)
+
+func SignAndDetach(content []byte, cert *x509.Certificate, privkey *rsa.PrivateKey) (signed []byte, err error) {
+	toBeSigned, err := NewSignedData(content)
+	if err != nil {
+		err = fmt.Errorf("Cannot initialize signed data: %s", err)
+		return
+	}
+	if err = toBeSigned.AddSigner(cert, privkey, SignerInfoConfig{}); err != nil {
+		err = fmt.Errorf("Cannot add signer: %s", err)
+		return
+	}
+
+	// Detach signature, omit if you want an embedded signature
+	toBeSigned.Detach()
+
+	signed, err = toBeSigned.Finish()
+	if err != nil {
+		err = fmt.Errorf("Cannot finish signing data: %s", err)
+		return
+	}
+
+	// Verify the signature
+	pem.Encode(os.Stdout, &pem.Block{Type: "PKCS7", Bytes: signed})
+	p7, err := pkcs7.Parse(signed)
+	if err != nil {
+		err = fmt.Errorf("Cannot parse our signed data: %s", err)
+		return
+	}
+
+	// since the signature was detached, reattach the content here
+	p7.Content = content
+
+	if bytes.Compare(content, p7.Content) != 0 {
+		err = fmt.Errorf("Our content was not in the parsed data:\n\tExpected: %s\n\tActual: %s", content, p7.Content)
+		return
+	}
+	if err = p7.Verify(); err != nil {
+		err = fmt.Errorf("Cannot verify our signed data: %s", err)
+		return
+	}
+
+	return signed, nil
+}
+```
+
+
+
+## Credits
+This is a fork of [fullsailor/pkcs7](https://github.com/fullsailor/pkcs7)