diff --git a/Cargo.lock b/Cargo.lock
index 2822106..f41ebe2 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -154,6 +154,28 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "equivalent"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
+
+[[package]]
+name = "errno"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "534c5cf6194dfab3db3242765c03bbe257cf92f22b38f6bc0c58d59108a820ba"
+dependencies = [
+ "libc",
+ "windows-sys",
+]
+
+[[package]]
+name = "fastrand"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9fc0510504f03c51ada170672ac806f1f105a88aa97a5281117e1ddc3368e51a"
+
 [[package]]
 name = "getrandom"
 version = "0.2.15"
@@ -165,6 +187,12 @@ dependencies = [
  "wasi",
 ]
 
+[[package]]
+name = "hashbrown"
+version = "0.14.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e5274423e17b7c9fc20b6e7e208532f9b19825d82dfd615708b70edd83df41f1"
+
 [[package]]
 name = "heck"
 version = "0.5.0"
@@ -177,6 +205,16 @@ version = "0.3.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d231dfb89cfffdbc30e7fc41579ed6066ad03abda9e567ccafae602b97ec5024"
 
+[[package]]
+name = "indexmap"
+version = "2.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "168fb715dda47215e360912c096649d23d58bf392ac62f73919e831745e40f26"
+dependencies = [
+ "equivalent",
+ "hashbrown",
+]
+
 [[package]]
 name = "is-terminal"
 version = "0.4.12"
@@ -216,6 +254,30 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "libyml"
+version = "0.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3e281a65eeba3d4503a2839252f86374528f9ceafe6fed97c1d3b52e1fb625c1"
+
+[[package]]
+name = "linux-raw-sys"
+version = "0.4.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78b3ae25bc7c8c38cec158d1f2757ee79e9b3740fbc7ccf0e59e4b08d793fa89"
+
+[[package]]
+name = "log"
+version = "0.4.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "90ed8c1e510134f979dbc4f070f87d4313098b704861a105fe34231c70a3901c"
+
+[[package]]
+name = "memchr"
+version = "2.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
+
 [[package]]
 name = "num-conv"
 version = "0.1.0"
@@ -276,9 +338,11 @@ dependencies = [
  "rio_api",
  "rio_turtle",
  "serde",
+ "serde_yml",
  "slog",
  "slog-async",
  "slog-term",
+ "tempfile",
 ]
 
 [[package]]
@@ -309,12 +373,31 @@ dependencies = [
  "rio_api",
 ]
 
+[[package]]
+name = "rustix"
+version = "0.38.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70dc5ec042f7a43c4a73241207cecc9873a06d45debb38b329f8541d85c2730f"
+dependencies = [
+ "bitflags",
+ "errno",
+ "libc",
+ "linux-raw-sys",
+ "windows-sys",
+]
+
 [[package]]
 name = "rustversion"
 version = "1.0.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "955d28af4278de8121b7ebeb796b6a45735dc01436d898801014aced2773a3d6"
 
+[[package]]
+name = "ryu"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f3cb5ba0dc43242ce17de99c180e96db90b235b8a9fdc9543c96d2209116bd9f"
+
 [[package]]
 name = "serde"
 version = "1.0.203"
@@ -335,6 +418,34 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "serde_json"
+version = "1.0.117"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "455182ea6142b14f93f4bc5320a2b31c1f266b66a4a5c858b013302a5d8cbfc3"
+dependencies = [
+ "itoa",
+ "ryu",
+ "serde",
+]
+
+[[package]]
+name = "serde_yml"
+version = "0.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ce6afeda22f0b55dde2c34897bce76a629587348480384231205c14b59a01f"
+dependencies = [
+ "indexmap",
+ "itoa",
+ "libyml",
+ "log",
+ "memchr",
+ "ryu",
+ "serde",
+ "serde_json",
+ "tempfile",
+]
+
 [[package]]
 name = "slog"
 version = "2.7.0"
@@ -389,6 +500,18 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f764005d11ee5f36500a149ace24e00e3da98b0158b3e2d53a7495660d3f4d60"
 
+[[package]]
+name = "tempfile"
+version = "3.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85b77fafb263dd9d05cbeac119526425676db3784113aa9295c88498cbf8bff1"
+dependencies = [
+ "cfg-if",
+ "fastrand",
+ "rustix",
+ "windows-sys",
+]
+
 [[package]]
 name = "term"
 version = "0.7.0"
diff --git a/Cargo.toml b/Cargo.toml
index 5834d8e..6eda731 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,3 +17,5 @@ clap = { version = "4.5.7", features = ["derive"] }
 rio_turtle = "0.8.4"
 rio_api = "0.8.4"
 bitflags = "2.5.0"
+serde_yml = "0.0.10"
+tempfile = "3.10.1"
diff --git a/src/io.rs b/src/io.rs
index 485913e..941100f 100644
--- a/src/io.rs
+++ b/src/io.rs
@@ -1,4 +1,6 @@
+use crate::rules::Config;
 use rio_turtle::NTriplesParser;
+use serde_yml;
 use std::{
     boxed::Box,
     fs::File,
@@ -18,7 +20,7 @@ pub fn get_reader(path: &Path) -> Box<dyn BufRead> {
 pub fn get_writer(path: &Path) -> Box<dyn Write> {
     return match path.to_str().unwrap() {
         "-" => Box::new(BufWriter::new(stdout())),
-        path => Box::new(BufWriter::new(File::open(path).unwrap())),
+        path => Box::new(BufWriter::new(File::create(path).unwrap())),
     };
 }
 
@@ -28,11 +30,22 @@ pub fn parse_ntriples(reader: impl BufRead) -> NTriplesParser<impl BufRead> {
     return NTriplesParser::new(reader);
 }
 
+// Parse yaml configuration file.
+pub fn parse_config(path: &Path) -> Config {
+    return match File::open(&path) {
+        Ok(file) => serde_yml::from_reader(file).expect("Error parsing config file."),
+        Err(e) => panic!("Cannot open file '{:?}': '{}'.", path, e),
+    };
+}
+
 #[cfg(test)]
 mod tests {
-    use super::parse_ntriples;
+    use super::{parse_config, parse_ntriples};
     use rio_api::parser::TriplesParser;
-    use std::io::{BufRead, BufReader};
+    use std::{
+        io::{BufRead, BufReader},
+        path::Path,
+    };
 
     #[test]
     // Test the parsing of a triple.
@@ -49,4 +62,10 @@ mod tests {
             })
             .expect("Error parsing triple");
     }
+    // Test the parsing of a config file.
+    #[test]
+    fn config_parsing() {
+        let config_path = Path::new("tests/data/config.yaml");
+        parse_config(&config_path);
+    }
 }
diff --git a/src/main.rs b/src/main.rs
index 3f0e177..a24b009 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -50,6 +50,11 @@ struct PseudoArgs {
     #[arg(default_value = "-")]
     input: PathBuf,
 
+    /// The config file descriptor to use for defining RDF elements to pseudonymize.
+    /// Format: yaml
+    #[arg(short, long)]
+    config: PathBuf,
+
     /// Output file descriptor for pseudonymized triples.
     /// Defaults to `stdout`.
     #[arg(short, long, default_value = "-")]
@@ -80,7 +85,7 @@ fn main() {
         }
         Subcommands::Pseudo(args) => {
             info!(log, "Args: {:?}", args);
-            pseudonymize_graph(&log, &args.input, &args.output, &args.index)
+            pseudonymize_graph(&log, &args.input, &args.config, &args.output, &args.index)
         }
     }
 }
diff --git a/src/pass_second.rs b/src/pass_second.rs
index cbaf866..54afdbd 100644
--- a/src/pass_second.rs
+++ b/src/pass_second.rs
@@ -10,6 +10,7 @@ use crate::{
     io,
     log::Logger,
     model::{pseudonymize_triple, TripleMask},
+    rules::Config,
 };
 
 fn mask_triple(triple: &Triple) -> TripleMask {
@@ -18,7 +19,12 @@ fn mask_triple(triple: &Triple) -> TripleMask {
 
 // mask and encode input triple
 // NOTE: This will need the type-map to perform masking
-fn process_triple(triple: &Triple, out: &mut impl Write) -> Result<(), TurtleError> {
+fn process_triple(
+    triple: &Triple,
+    rules_config: &Config,
+    node_to_type: &HashMap<String, String>,
+    out: &mut impl Write,
+) -> Result<(), TurtleError> {
     let mask = mask_triple(triple);
     let pseudo_triple = pseudonymize_triple(&triple, mask);
     let _ = out.write(&format!("{} .\n", &pseudo_triple.to_string()).into_bytes());
@@ -41,32 +47,42 @@ fn load_type_map(input: impl BufRead) -> HashMap<String, String> {
     return node_to_type;
 }
 
-pub fn pseudonymize_graph(log: &Logger, input: &Path, output: &Path, index: &Path) {
+pub fn pseudonymize_graph(log: &Logger, input: &Path, config: &Path, output: &Path, index: &Path) {
     let buf_input = io::get_reader(input);
     let buf_index = io::get_reader(index);
     let mut buf_output = io::get_writer(output);
+    let rules_config = io::parse_config(config);
 
     let node_to_type: HashMap<String, String> = load_type_map(buf_index);
     let mut triples = io::parse_ntriples(buf_input);
     while !triples.is_end() {
         triples
-            .parse_step(&mut |t| process_triple(&t, &mut buf_output))
+            .parse_step(&mut |t| process_triple(&t, &rules_config, &node_to_type, &mut buf_output))
             .unwrap();
     }
 }
 #[cfg(test)]
 mod tests {
-    use super::encrypt;
+    use super::pseudonymize_graph;
     use crate::log;
     use std::path::Path;
+    use tempfile::tempdir;
 
     #[test]
     // Test the parsing of a triple.
     fn encrypt_nt_file() {
+        let dir = tempdir().unwrap();
         let input_path = Path::new("tests/data/test.nt");
-        let output_path = Path::new("tests/data/output.nt");
+        let config_path = Path::new("tests/data/config.yaml");
+        let output_path = dir.path().join("output.nt");
         let type_map_path = Path::new("tests/data/type_map.nt");
         let logger = log::create_logger(true);
-        encrypt(&logger, &input_path, &output_path, &type_map_path);
+        pseudonymize_graph(
+            &logger,
+            &input_path,
+            &config_path,
+            &output_path,
+            &type_map_path,
+        );
     }
 }
diff --git a/src/rules.rs b/src/rules.rs
index 9e201ad..c00452e 100644
--- a/src/rules.rs
+++ b/src/rules.rs
@@ -1,13 +1,14 @@
+use ::std::collections::{HashMap, HashSet};
 use serde::{Deserialize, Serialize};
 
 #[derive(Serialize, Deserialize, Debug)]
-struct Config {
+pub struct Config {
     // Replace values of nodes with a certain type.
-    replace_values_of_nodes_with_type: Vec<String>,
+    pub replace_uri_of_nodes_with_type: HashSet<String>,
 
     // Replace values of `subject` & `predicate`.
-    replace_values_of_subject_predicate: Vec<(String, String)>,
+    pub replace_values_of_subject_predicate: HashMap<String, HashSet<String>>,
 
     // Replace values in matched `predicates`.
-    replace_value_of_predicate: Vec<String>,
+    pub replace_value_of_predicate: HashSet<String>,
 }
diff --git a/tests/data/config.yaml b/tests/data/config.yaml
index 085fa43..6d1d791 100644
--- a/tests/data/config.yaml
+++ b/tests/data/config.yaml
@@ -1,15 +1,15 @@
-# Hash URIs of people and online accounts.
-replace-uris-of-nodes-with-type:
-  "http://xmlns.com/foaf/0.1/Person" # All nodes which are `rdf:type Person`.
-  "http://xmlns.com/foaf/OnlineAccount" # or `rdf::type OnlineAccount`
+# hash URIs of people and online accounts
+replace_uri_of_nodes_with_type:
+  - "http://xmlns.com/foaf/0.1/Person" # All nodes which are rdf:type Person
+  - "http://xmlns.com/foaf/OnlineAccount" # "" OnlineAccount
 
-# Hash name only for instances of person and online account.
-replace-values-of-predicate-object:
+# hash name only for instances of person and online account
+replace_values_of_subject_predicate:
   "http://xmlns.com/foaf/OnlineAccount":
-    "http://schema.org/name"
+   - "http://schema.org/name"
   "http://xmlns.com/foaf/0.1/Person":
-    "http://schema.org/name"
+   - "http://schema.org/name"
 
-# Hash accesscode values for all nodes.
-replace-values-of-predicate:
-  "http://schema.org/accessCode"
\ No newline at end of file
+# hash accesscode values for all nodes
+replace_value_of_predicate:
+  - "http://schema.org/accessCode"